Window order checking / comparing suppliers

[craig]

I thought I would put a post together for those that are looking for windows, replacement or new build. As someone who deals with final order placing / final quote discussions. One of the things that crosses my desk on regular basis, is that the "other supplier" is more cost effective. Which leads me to ask myself "more cost effective against what" are you comparing apples for apples? When I ask people to compare, what we generally explain is to look at the following (see below) if they are not willing to supply a copy of the quote without prices.

 

• Product - is the product similar. For example are you comparing a Timber Aluminium cladded window with a Timber Aluminium cladded window?
• Glazing - Is the glazing on offer from both suppliers comparable? Is it double glazed v's triple glazed for example or is it float glass v's toughened or laminate?
  • Check that doors have toughened/laminated glazing
  • Check that windows within 300mm of a door have toughened/laminated glazing
  • Check that windows below 800mm from the finish floor have toughened/laminated glazing
  • Check that windows that are 1400mm in height or above for toughened/laminated glazing. Most suppliers will start to consider toughened / laminated from 1400mm onwards, some will still be float glass.
  • Check triple glazed glass units. Some suppliers will only toughen the inner and outer panes and leave the middle pane as float glass, others will toughen all 3 panes (I recommend all 3 panes as toughened) when required. Why? quick example is from experience, a customer in the north west of Scotland had the middle pane as float glass in french doors, the doors are recessed with wall on either side. It effectively became a wind tunnel. What happened is during high winds, the door sashes had that much wind pressure constantnly, that the door sash was pushed away from the frame slightly and a rattle effect occurred (only thing I could think would cause this to happen). As a result the middle pane (float glass) shattered. This required the whole sash to be replaced, as the glass was glued into the frame on that particular product.
• Timber - Is the timber comparable, are both using spruce/larch/oak/pine etc.? Are any of the products finger jointed as standard (which is more cost effective versus fixed timber, but not as aesphetically pleasing). Is the timber cut from from one section of wood or is it individually glue laminated timber?
• Ug values - A 0.5Ug can be quoted by suppliers but the costs vary dramatically. One of the reasons for this can be the glass make up and the gas that is being used. Some quotes won't tell the gas being used but it's safe to assume that if it's 48mm glazing it is Argon. Pay attention to the spacer distance also, not for cost but if the spacer is above 18mm, convection can occur of the gas filling (gas moves around in the unit).
• Hinging - Are the hinges concealed or are they exposed?
• Door Hinging - Pay close attention as suppliers will have quoted standard framing on doors, others may have increased the widths of the jambs to increase the space available at the hinging for plastering behind. 
• RAL Colours externally - are the quoted RAL colours the same?
• Internal colours - have they quoted the same? Some will offer the standard colours such as a clear lacquer, others will have them painted - does this have any impact on price comparison.
• Sizes - have any of the units been split, due to not being able to achieve the size required? Some suppliers will not be able to do large sizes, others will be. Look out for compromises.

 

Don't always look at the end figure and immediately reject a quote as being to high, compared to the others.

 

Most suppliers will have the supply price first, then additional items such as window cills, compriband, membrane, installation etc. which are optional to the quote and not necessarily required but may be included in the total cost at the end. Most self builders like to take on the mantra of doing the whole build, others would like to leave this to the supplier or builder and or source their own materials if supply only.

 

• What is being offered with the installation service, are the installation options / costs comparible to each other?
• Who takes responsibility for the windows upon arrival? Generally speaking most suppliers who are installing, should be taken responsibility from the moment the windows leave the factory, to the moment the windows/doors have been installed, sign off. If supply only, the responsibilitygenerally passes to the client once the offload commences. So it is important to document the windows before offload, during offload and once offloaded. The manufacturer will normally have documentation / pictures before departing the factory, it makes life easier on whether a claim with the haulage company or whether a claim with the supplier is required (both should go to the supplier who should deal with it).
• Warranty - how long is the warranty, what does it cover?

 

Last but not least, is the quote comparible? Have the suppliers referenced things the same way or are have the drawings been scaled and then referenced by the supplier (this happens a lot when no window schedule exists)? A lot of architects don't create window schedules for some reason (one the major parts of a build and most costly aspects) and problems of missing windows can be encountered, due to the elevations not always showing "hidden" windows which can be seen on floor plans. Some suppliers can miss this, which then impacts that quote. 

Hopefully some people find this useful, of not apologies for the long read 

Edited June 12, 2017 by craig

[MikeSharp01]

Very helpful and insightful.

 

[Jeremy Harris]

It's very useful, as we found that one supplier, Internorm, didn't include any of the necessary "extras" in their quote.  When we added in installation, cills etc their quote rose by a whopping £4k, and they were already the highest quote we had.  In contrast, Munster included everything in their quote, but I asked them to leave out sealing, as I wanted to do it, just to be absolutely certain that the low expansion foam was right through the full depth of the pretty thick frames.   It took me a fair while, using a specially made 2mm nozzle, to inject foam from both inside and outside around every frame, but I wanted to ensure that there was as little chance as possible of there being any cold air bridges around the edges.

[craig]

17 hours ago, JSHarris said:

It's very useful, as we found that one supplier, Internorm, didn't include any of the necessary "extras" in their quote.  When we added in installation, cills etc their quote rose by a whopping £4k

 

Oh I've quoted projects and been £10K / £20K + more expensive than others. Its not til you sit down are able to compare competitors quotes you can see the difference. One particular one springs to mind of a 6.6 metre lift and slide door one fixed, one slide at 3m height, ours was double the price but it's not til you look at the details you realise the difference.

 

Triple glazed you are looking at half a tonne + for the sliding element. Standard gearing doesn't cut the mustard so needs to be double gearing/electrical assistance. It was also a 90 degree corner and I worked out a specific detail for the corner which coupled to a standard fixed window. You can't just couple a 92mm frame to a 217mm frame on a corner detail.

 

Its only when you look at these things you see why.

Edited June 13, 2017 by craig

[Monty Gerhardy]

On 12/6/2017 at 15:53, craig said:

I thought I would put a post together for those that are looking for windows, replacement or new build.

You make no mention of;

·         Basic performance testing – watertightness, air permeability, strength. Likewise cyclic-testing or corrosion resistance.

·         Certification/3rd-party assessment of suitability for UK conditions

·         Security testing.

 Glazing.

·         There is no specific requirement for units taller than 1400mm to have toughened glass.

·         The doors sold to your customer must have either been rubbish or totally unsuitable for the location if they were vibrating so much that a pane of glass shattered.  Incidentally, I  regard the vibration theory causing breakage as implausible.

Timber

·         If softwoods are being used - which is the most common timber for windows - the form of preservative treatment is of particular significance.

Ug

·         Not as important as Uw. You also make no mention of g-value – high solar gain with a lack of shading is a problem with large areas of south facing glazing. ‘A’ rated sounds great in theory but can often lead to sauna like conditions in a highly insulated building.

Hinges

·         Function over form. Of far more importance then visibility is the load rating, durability of the hinge finish and potential for adjustment.

 

A few other things to look out for;

·         Are all the windows and doors from the same factory/manufacturer?  If not profiles will vary, as may colours, ironmongery and even glass colour.

·         Does the warranty come from the manufacturer or the agent/distributer? What happens to the warranty if agent goes bust?

·         Is the system designed for UK weather/building conditions or Central European climates? 

·         If to be used in areas of severe or very severe exposure (see BRE 262) can the system accommodate a checked reveal as required by NHBC?  Is it a drained and ventilated design ?

·         Has the glazing been sized to accommodate the wind loadings?

·         Has glazing been sized to accommodate any barrier loading requirement at higher levels ?

·         Are units being joined together and have these couplings been assessed by an engineer?

·         Does the product certification cover the size of unit being supplied ? Does the certification relate to all the products being supplied ?

 

 

[craig]

1 hour ago, Monty Gerhardy said:

You make no mention of;

 

·         Basic performance testing – watertightness, air permeability, strength. Likewise cyclic-testing or corrosion resistance.

 

·         Certification/3rd-party assessment of suitability for UK conditions

 

·         Security testing.

 

No, the reason for this, is it's a quotation and usually will not cover this and usually irrelevant to a quote comparison. The points you raised are covered by indepenent 3rd party certificates in most circumstances and not covered in a quotation.

 

1 hour ago, Monty Gerhardy said:

Glazing.

 

·         There is no specific requirement for units taller than 1400mm to have toughened glass.

 

·         The doors sold to your customer must have either been rubbish or totally unsuitable for the location if they were vibrating so much that a pane of glass shattered.  Incidentally, I  regard the vibration theory causing breakage as implausible.

 

No specific requirement but it is standard practice with most manufacturers and a safety aspect to toughen glass when the height is in those regions. 

 

As for the doors. You are making either an ill informed opinion or you have no experience of this issue. All units will be tested to a certain class / pascal rating. That particular system is tested to 1800 pascal rating which is in excess of 120mph wind speeds, the security class of the system is WK2 and 5 point locking.  If you think a tunnel effect is implausible, then supply an alternative theory. 

 

As for being rubbish, that they are not - I assure you of that (check out my introduction for more information).

 

Fact is, the wind pressure against the sash was forcing the sash away from the frame. So with the wind pressure increasing/decreasing over several hours it appears that has caused the sash to hit the frame by causing a couple mm gap and has been repeated over several hours has likely been the cause of the issue. It is the only explanation we can think of that would have caused it and without put the unit in a wind tunnel to test, the only logical explanation (from myself and several others).

 

1 hour ago, Monty Gerhardy said:

 

 

·         If softwoods are being used - which is the most common timber for windows - the form of preservative treatment is of particular significance.

 

Again, not shown on a quotation and dealt with via certificates and therefor not always relevant for comparison checks.

 

1 hour ago, Monty Gerhardy said:

Ug

 

·         Not as important as Uw. You also make no mention of g-value – high solar gain with a lack of shading is a problem with large areas of south facing glazing. ‘A’ rated sounds great in theory but can often lead to sauna like conditions in a highly insulated building.

 

I never said it was. Therefor, please don't imply other wise. What I said was

On 6/12/2017 at 15:53, craig said:

Ug values - A 0.5Ug can be quoted by suppliers but the costs vary dramatically. One of the reasons for this can be the glass make up and the gas that is being used

 

I specifically didn't mention Uw values, the main reason being they become extremely important within PHPP calculations for a PassivHaus where the space psi value can be the difference between a pass or a fail. Otherwise, it is not the sole reason for a customers choice but it is worth checking in the comparison and in hindsight should have been mentioned.

 

1 hour ago, Monty Gerhardy said:

Hinges

 

·         Function over form. Of far more importance then visibility is the load rating, durability of the hinge finish and potent

 

Again, not covered within a quotation. This will be in certificates and installation/adjusment manuals and therefor not relevant to a quote comparison.

 

1 hour ago, Monty Gerhardy said:

A few other things to look out for;

 

·         Are all the windows and doors from the same factory/manufacturer?  If not profiles will vary, as may colours, ironmongery and even glass colour.

 

·         Does the warranty come from the manufacturer or the agent/distributer? What happens to the warranty if agent goes bust?

 

·         Is the system designed for UK weather/building conditions or Central European climates? 

 

·         If to be used in areas of severe or very severe exposure (see BRE 262) can the system accommodate a checked reveal as required by NHBC?  Is it a drained and ventilated design ?

 

·         Has the glazing been sized to accommodate the wind loadings?

 

·         Has glazing been sized to accommodate any barrier loading requirement at higher levels ?

 

·         Are units being joined together and have these couplings been assessed by an engineer?

 

·         Does the product certification cover the size of unit being supplied ? Does the certification relate to all the products being supplied ?

 

All valid points but again, not covered under a quote comparison but some quotes will advise of the relevant BS/EN EN numbers on the quotes. Most customers will not be aware of these and it is the suppliers/manufacturers responsibilty to supply this information. As well as supplying a performance declaration for all units supplied within any installation.

Edited June 13, 2017 by craig

[ProDave]

Can I ask a window related question for our new expert?

 

One of our windows we bought without glass, because we want a stained glass panel in that one.  I am close to looking to source the glass for this.

 

I know the visible size of the window (i.e the internal size of the opening in the frame)  I also know that the frame where the glass sits is 40mm bigger in both dimensions (20mm each side)  What I need to know is what glass size do I specify? which I guess means how much gap from the edge of the glass to the edge of the frame?

 

And the second question is do you know someone that will make up a tripple glazed panel, 50mm overall thickness, plain glass outside, stained glass panel in the middle, toughened glass on the inside. The unit is 600mm wide by 1750 tall (visible glass size)

[Jeremy Harris]

6 minutes ago, ProDave said:

Can I ask a window related question for our new expert?

 

I believe that both @Monty Gerhardy and @craig have a commercial interest in supplying windows, so perhaps, in the interest of being fair to both businesses, that question should be addressed to both?

 

Personally, I'm opposed to anyone using this forum as a way of getting free, thinly disguised, advertising.................

[ProDave]

The question was really aimed at anyone that knows an answer. So far suppliers of bare 3G stained glass window panels are thin on the ground. Our local plastic window supplier will make one but I am not convinced of their quality (the replacement 2G panes they fitted in our old house were noticable poorer than the originals that they replaced)

 

There are quite a few "artists" that will make you a bespoke stained glass panel to your design at a horendous price. Most of them are not interested in shipping it so you would have to collect it.

 

All we want is a simple stained glass panel for a landing window. It wants a fair bit of plain glass, so thinking of something with a stained glass border and a stained glass feature in the middle with plain glass around it. the sort of thing commonly used for front doors.  Happy to select from a few standard designs rather than bespoke.

[craig]

33 minutes ago, JSHarris said:

 

I believe that both @Monty Gerhardy and @craig have a commercial interest in supplying windows, so perhaps, in the interest of being fair to both businesses, that question should be addressed to both?

 

Personally, I'm opposed to anyone using this forum as a way of getting free, thinly disguised, advertising.................

 

Agreed I'm not here to advertise in anyway. Purely joined here to give assistance if I can and to participate.

[craig]

2 hours ago, ProDave said:

Can I ask a window related question for our new expert?

 

One of our windows we bought without glass, because we want a stained glass panel in that one.  I am close to looking to source the glass for this.

 

I know the visible size of the window (i.e the internal size of the opening in the frame)  I also know that the frame where the glass sits is 40mm bigger in both dimensions (20mm each side)  What I need to know is what glass size do I specify? which I guess means how much gap from the edge of the glass to the edge of the frame?

 

And the second question is do you know someone that will make up a tripple glazed panel, 50mm overall thickness, plain glass outside, stained glass panel in the middle, toughened glass on the inside. The unit is 600mm wide by 1750 tall (visible glass size)

 

Of course.

 

The difficulty is not knowing which system. Is it wet or dry sealed, is the glass glued or packed. You'll usually have about 4 to 6mm around the frame for packing

 

(This is three different window systems for comparison)

 

Regarding the triple glazed stained glass, it's one of those custom units and I have also tried in the past and baulked at the prices and advised customers if required, they will need to source it themselves (sorry).

[ProDave]

Thanks Craig

 

My windows are Rationel if you know them in detail? Looks more like the left hand of your drawings although their aluminium profile is a lot less bulky.

 

Looking at the bare window frame, what I have is a recess on the outside that the glass "fits" into, somehow. Then an aluminium surround goes on from the outside (the windows are all ali clad timber) So I had assumed the glass fits to the frame with double sided glazing tape, using wedge packers to position it and get it square. The rest of the windows that came pre glazed you can see a thin bit of grey rubber / foam between the frame and the glass on the inside which I assume to be double sided tape.  The aluminium outside trip has a rubber profile built in to seal to the outside of the glass, though I am not sure yet what holds that trip in place.

 

What I am wanting to know is what size to specify the glazing unit. If you say a 4 to 6mm gap, and I have 20mm "available" then it sounds like they need to be about 15mm larger on each side than the visible glass area so 30mm bigger in each dimension overall.

 

Another way to address the question it, is what is the thickness of the spacer that goes around the edge to separate the 3 sheets of glass.  All the pre glazed windows, the edge of the frame lines up with the inner visible face of the edge spacer (sorry no doubt wrong terminology) so if say that spacer strip was 15mm wide it would reinforce the make it 30mm bigger idea?

[craig]

Rational AuraPlus - Tilt & Turn?

 

Head and Cill

 

 

Jambs

[ProDave]

I don't suppose you have the drawing for the fixed pane version (this window is fixed)

 

I seem to have a "problem" here.  The window in question was supplied, unglazed. The aluminium trim is in two parts, one that covers the wooden frame, and one that covers just the edge of the glass, with no clear way of attaching the trim over the glass other than tape.

 

I have two more fixed pane windows in the house and they came pre glazed. It appears on those, the trim is all one piece covering the frame and the glass in one go, and it's easy to see how that clips the the wooden frame.

 

That's a question I need to address to Rationel when I have the glass. but for now it looks like 4mm gap at each side  looks favourite.

[craig]

Head and cill Aura Plus Fixed

 

 

Jambs

[ProDave]

Yes that confirms what I thought, that normally the cladding is all one piece, but mine is split to allow the glazing to be fitted later. I will have to seek guidance from Rationel how to fit my split surround.

 

It also raises another issue. Should I be unfortunate enough to break a window in one of the fixed windows, there is no way to remove the trim to change the unit without hacking the render off then re doing the ingo's.

[craig]

The probem of windows being glazed from the external side I'm afraid. Most alu clad windows externally glazed, will require the cladding to be removed "if the cladding goes all the way to the end of the frame or it sits behind the the outer wall". 

 

Internally glazed in my view and others, are better options for maintenance and for security.

Edited June 14, 2017 by craig

[ProDave]

I have had a look around all my different windows. The two single fixed pane ones are the only ones that have the cladding in one piece going under the render.

 

Where I have two panes, one opening and one fixed next to each other, the fixed pane has been done like my stained glass window, with a separate trim around just the glass. I just need to check with Rationell how that trim is secured.

 

In a previous house, we had externally fitted UPVC doors and windows. We had an attempted break in where the perpetrators removed the external beading, but removing the glass stuck in with double sided foam tape defeated them.  The police logged it as "criminal damage" rather than attempted burglary.  So I am not concerned about security.

 

I documented my search for windows on a previous forum. I had quotes from about half a dozen quality window suppliers. It was an easy choice as Rationel were the cheapest and almost the best. Only Internorm had a very slightly better Uw value, but at twice the price and the most expensive by a long way.  All I wanted was good 3G windows with aluminium cladding. Whether they were internally or externally fitted glass was not a consideration.

 

I have to say I am very pleased with the very simple crisp external and internal detail of the Rationel windows.

[craig]

Absolutely, not every window system suits everybody - the slim profiles is what a lot of people look for.

[Monty Gerhardy]

23 hours ago, craig said:

 

No, the reason for this, is it's a quotation and usually will not cover this and usually irrelevant to a quote comparison. The points you raised are covered by indepenent 3rd party certificates in most circumstances and not covered in a quotation.

Your ‘quote comparison’ reads like a non to subtle sales pitch.  “Are any of the products finger jointed as standard (which is more cost effective versus fixed timber, but not as aesphetically pleasing)….Hinging - Are the hinges concealed or are they exposed?”  Somewhat subjective I would have thought

23 hours ago, craig said:

As for the doors. You are making either an ill informed opinion or you have no experience of this issue. All units will be tested to a certain class / pascal rating. That particular system is tested to 1800 pascal rating which is in excess of 120mph wind speeds, the security class of the system is WK2 and 5 point locking.  If you think a tunnel effect is implausible, then supply an alternative theory. 

 

Thermal stress – not at all unusual for an annealed middle pane of a triple-glazed unit.

23 hours ago, craig said:

As for being rubbish, that they are not - I assure you of that (check out my introduction for more information).

“This required the whole sash to be replaced, as the glass was glued into the frame on that particular product.”  Q.E.D.

23 hours ago, craig said:

 

Fact is, the wind pressure against the sash was forcing the sash away from the frame. So with the wind pressure increasing/decreasing over several hours it appears that has caused the sash to hit the frame by causing a couple mm gap and has been repeated over several hours has likely been the cause of the issue. It is the only explanation we can think of that would have caused it and without put the unit in a wind tunnel to test, the only logical explanation (from myself and several others).

I’ve seen IGU’s flex in the region of 20mm – in/out, in/out -  like the diaphragm of an amplifier under loads in excess of 3000Pa in a test rig. Deflection of glazing up to 25mm is acceptable.  In addition to the inherent flexibility of the glass the spacer bar/sealant will absorb stresses.  The wet or dry glazing gasket will absorb stress between IGU and frame.  Last but not least there will be a weatherseal gasket between the door leaf and door frame that will also absorb shock.  If it’s not thermal stress then a sharp sudden impact like a ball or bird would be far more plausible.

23 hours ago, craig said:

I never said it was. Therefor, please don't imply other wise. What I said was

 

Obfuscation –  I clearly didn’t quote you or imply anything.

23 hours ago, craig said:

 

I specifically didn't mention Uw values, the main reason being they become extremely important within PHPP calculations for a PassivHaus where the space psi value can be the difference between a pass or a fail. Otherwise, it is not the sole reason for a customers choice but it is worth checking in the comparison and in hindsight should have been mentioned.

Reverse ferret

[Monty Gerhardy]

13 hours ago, ProDave said:

All we want is a simple stained glass panel for a landing window. It wants a fair bit of plain glass, so thinking of something with a stained glass border and a stained glass feature in the middle with plain glass around it. the sort of thing commonly used for front doors.  Happy to select from a few standard designs rather than bespoke.

If you are set on this approach you want to search for glaziers that can supply ‘encapsulated glazing units’. Personally  I’m not a fan. Thermally they are usually not great given the narrow cavities, lack of soft-coat LowE and gas filling. I also remain to be convinced about the durability of the perimeter sealing.

I would recommend having a standard IGU installed in the window frame in the normal fashion (thus maintaining the integrity of the thermal/physical  envelope along with manufacturers warranty) and then have an encapsulated unit framed within an alu U-channel sized to fit in the internal reveal of the frame.  Done well it would be barely noticeable.

You also mention that the window is on a landing. Without railings or a physical barrier the glazing should be designed to take barrier loadings.

[Monty Gerhardy]

8 hours ago, ProDave said:

Yes that confirms what I thought, that normally the cladding is all one piece, but mine is split to allow the glazing to be fitted later. I will have to seek guidance from Rationel how to fit my split surround.

 

It also raises another issue. Should I be unfortunate enough to break a window in one of the fixed windows, there is no way to remove the trim to change the unit without hacking the render off then re doing the ingo's.

Not sure that you are getting the right steer from the drawings that have been put up

What you have is probably as illustrated in attached pdf

The claddings are a compression fit - the video may give a bit more context.

https://www.youtube.com/watch?v=DAlTAH-WHUY

auraplus-tgu-windows2.pdf

[Monty Gerhardy]

7 hours ago, craig said:

The probem of windows being glazed from the external side I'm afraid. Most alu clad windows externally glazed, will require the cladding to be removed "if the cladding goes all the way to the end of the frame or it sits behind the the outer wall". 

 

Internally glazed in my view and others, are better options for maintenance and for security.

If that’s what you are flogging then Mandy Rice Davies dictum comes to mind.

In the view of TRADA (Wood windows: Designing for high performance) and NHBC (Standards 6.7) drained and ventilated designs (externally beaded) are recommended for areas of severe and very severe  exposure to wind driven rain (see map, Standards 6.1)

The security issue is a non-sequitur. The AuraPlus window is SBD licensed as are numerous other externally glazed alu-clad timber windows.

[craig]

@Monty Gerhardy Sorry I don't know you, I don't know your profession but you are obviously in the window industry.

 

You come across as a very arrogant and rude man and I have no time for that, I may be wrong and I hope I'am.

 

However, you are bringing this way off topic and in my view personal and I would kindly ask you to refrain from doing so.

 

I'm also not going to get into any argument but your attack is not welcome.

Edited June 14, 2017 by craig

[Jeremy Harris]

Folks, I have very strong feelings about this forum being allowed to be used by commercial entities, and this thread exemplifies why I think that forum policy regarding commercial use needs to be tightened.

 

It's inevitable when we get competing commercial interests, in the same sector, as in this case, that they will end up being critical of each other in order to try and gain some sort of commercial advantage.  The fact that it may well tend to make many of the potential customers of this non-commercial, member owned and run, forum, think again about using any commercial entities that misuse this forum is a point that seems to be lost.

 

As one of the founder members that invested time and money in setting up this non-commercial forum, I think it's time that we gave a reminder to all who use it that it is NOT a place for commercial entities to promote their wares or raise their own profile.

 

This forum was founded by a group of fourteen volunteers, who invested their own money and time to set it up and who, with the generosity of other members, pay the costs of hosting it.  Will our members that are in business related to self build and renovation please take note of this, and that people like me are paying to give them a vehicle to promote themselves on here, something I find abhorrent.

Edited June 15, 2017 by JSHarris