Windows Fixing Detailing - Provided by Architect or Window Supplier?

[mike2016]

I had an almighty row with my proposed window supplier yesterday and I wanted to fact check their statements to me a bit. We're in a standoff over this issue and I'm having to pivot and find a new supplier as a result. I won't mention who it is but from the general experience of the forum members - who specifies the window installation & fixing details based on weight / wind loads etc? Is it an Architect or the Window Supplier or other? 

The Window Sales Rep insists its always the Architect, they've never supplied any windows without the Architect supplying the installation detailing / fixing details. I tried arguing what happens in a retrofit with no Architect, they pivoted to well a deep retrofit would always have an Architect..... 

I asked my Architect and they said no, they never do this. The window installers look after that. They will inspect the work and point out if something looks "off" like a single window strap per side instead of 2 or 3 etc but that's all. 

So, unless a Structural Engineer provides this information but my builder says this is standard detailing and no they don't do this either. 

 

I'm at a loss - the price was great, performance good enough and we were working through some insulation detailing which is a bit unusual perhaps to them (thermal buck in the window openings) but I provided detailed drawing sections and photographs of what I was after, easy to coordinate and I would be happy with the window suppliers recommendations for fixing locations but they refused to work with me on this point blank.

 

Anyway, what happens out in the real world, do you just provide the rough opening measurements with a 10mm wiggle room and the installers work out the fixings onsite as they are meant to or does everyone have fixing details provided by their Architects? Thanks! 

 

[ToughButterCup]

Opening measurements to a couple of mm. Installers fix. Gaulhofer.

 

Architects sometimes argue - that whatever they specify, the installers  do what they want.  And the installers say, the architects don't know what happens in practice so they have to sort it out.  The Gaulhofer  team were good - not excellent. We needed to ask one specialist to come and sort out our very heavy doors. The architect was not invlved at all.

[Thorfun]

4 minutes ago, mike2016 said:

Anyway, what happens out in the real world, do you just provide the rough opening measurements with a 10mm wiggle room and the installers work out the fixings onsite as they are meant to or does everyone have fixing details provided by their Architects?

For us we provided the window company (Norrsken) with the opening size the TF company would provide and they built the windows to fit with their standard tolerance subtracted from the opening size. Then the installers turned up and fitted. No one ever asked me to provide a fixing schedule or the like. The fitters just did what they do and made sure the windows were secure with the number of fixings they thought suitable. 
 

sounds like a serious case of ‘arse covering’ by your window supplier. 

[Russell griffiths]

I’m afraid I think your wrong, they are suppling a product, you might do something random with it like fit it in a shipping container house, if you have specific fitting requirements then your architect should supply a drawing. 

You might go to them and ask if they can advise on fittings per window according to weight. 

 

From my experience this last couple of years you are far better off just getting some windows and then designing the fitting method and employing a couple of good lads to fit them to your spec. 

The window fitters will want to chuck them in as fast as possible and off to the next job. 

 

Unless you are having a one off bespoke door system that requires weeks of discussion between architect and window supplier. 

[Kelvin]

Our timber kit company has supplied construction drawings showing window and fitment detailing. The only involvement our window supplier had was agreeing the maximum weight and size for one of the sliding doors and will attend site when this particular window is being installed. Our window supplier only do supply and don’t get directly involved in fitting. 
 

Therefore I agree Russell it’s up to your architect to provide any specific details or the window fitter. If you’re doing something unusual and don’t have an architect then it’s on you. 

Edited March 23, 2023 by Kelvin

[saveasteading]

There are multiple interfaces in construction where the responsibility is blurred. 

The window manufacturer doesn't measure opening sizes, check the suitability of the structure, or tell you how to fix the frames.

 

If the glass breaks next year through stresses, who's issue is it....yours.

 

You can, if prepared to pay for the service and them taking the risk, get a supply and fit service. They tend to use one or 2 systems and have their methods of fixing. They also make their own assessment of tolerances around the window.

 

Missing out middle men means you take on more risk and management.

 

10mm wriggle room. Yes about that although one guy told me he allowed 20mm on upstairs windows because nobody can see it!  I didnt use him. 

Make sure this 10mm is outside the rectangle that the window will be, as openings may not be 'square'. 

[mike2016]

I'll be measuring off the erected timber frame and they can build in whatever tolerances they want. This was a supply and fit service but they just didn't want to own ANY risk it seems....

[Thorfun]

2 hours ago, Thorfun said:

For us we provided the window company (Norrsken) with the opening size the TF company would provide and they built the windows to fit with their standard tolerance subtracted from the opening size. Then the installers turned up and fitted. No one ever asked me to provide a fixing schedule or the like. The fitters just did what they do and made sure the windows were secure with the number of fixings they thought suitable. 
 

sounds like a serious case of ‘arse covering’ by your window supplier. 

i should probably clarify that Norrsken arranged the fitters as well so it was all, kind of, in-house. maybe different if the fitters are 3rd party as then it could all become a blame game.

[saveasteading]

6 minutes ago, mike2016 said:

They can build in whatever tolerances they want. 

How nice for them that they can deny expertise and risk.

It is risky that you have to measure the openings, they don't know how accurately you have done it, and they decide tolerances.

On our project we bought the units direct. Even as seasoned experts we made a costly mistake with a window into an irregular opening. 

 

Good idea to switch I think. 

[Thorfun]

12 minutes ago, mike2016 said:

I'll be measuring off the erected timber frame and they can build in whatever tolerances they want. This was a supply and fit service but they just didn't want to own ANY risk it seems....

this is a very slow way of doing it although it does reduce the risk. windows tend to be on at least a 12 week lead time and so you're TF won't be watertight for at least 3 months after erection (depending on when the roof goes on of course). our windows were ordered off-plan and the TF company then built to the correct dimensions. meant we could get the windows in as soon as the roof covering was on without having to wait for the windows to be manufactured. i thought most building with TF did it this way? one of the benefits of building in timber is the accuracy that can be achieved over block and brick.

[mike2016]

My Timberframe supplier is very adamant not to measure off plans. It does mean longer scaffolding rental costs and dry in period unfortunately but then all the risk is on the window supplier, they do the measurements and we can confirm onsite and if they get it wrong its on them but way slower I know. One supplier has a 4 week leadtime but I'm not sure their "high end" windows are good enough / fitted well enough and their after sales is terrible but that's who the timberframe provider recommended so it normally works out for them. I trust the timberframe guy, he's good, just cautious but I'm chasing very strict performance criteria and have a narrow range of acceptable window suppliers I'd prefer to use....

[Mr Punter]

Be aware that with timber frame and brick / block outer leaf the installation has to take account of differential movement, so over time the gap at the head of the window will open up and the cill will close up, especially on upper floors.  This is where the likes of Compriband are very handy.

[PeterW]

2 hours ago, mike2016 said:

Anyway, what happens out in the real world, do you just provide the rough opening measurements with a 10mm wiggle room and the installers work out the fixings onsite as they are meant to or does everyone have fixing details provided by their Architects? Thanks! 

opening -50mm on timber frame and then box out using 12 or 18mm exterior ply and you can create a very good airtight box to the correct depth. 

[Kelvin]

37 minutes ago, mike2016 said:

My Timberframe supplier is very adamant not to measure off plans. It does mean longer scaffolding rental costs and dry in period unfortunately but then all the risk is on the window supplier, they do the measurements and we can confirm onsite and if they get it wrong its on them but way slower I know. One supplier has a 4 week leadtime but I'm not sure their "high end" windows are good enough / fitted well enough and their after sales is terrible but that's who the timberframe provider recommended so it normally works out for them. I trust the timberframe guy, he's good, just cautious but I'm chasing very strict performance criteria and have a narrow range of acceptable window suppliers I'd prefer to use....

Interesting approach. Our timber kit and windows are being installed at the same time. 

[craig]

The window supplier should be checking the wind data for your area on large items (especially when coupled), installation position/detail is generally set out on drawings by the architect and finessed by the supplier/installer. Sizes on new builds are based on the known structural opening, usually taken from as-built or confirmed frame sizes for example.

 

Tolerance requirements are different on different windows/suppliers but a rule of thumb is 5mm or 10mm. 

Edited March 23, 2023 by craig

[saveasteading]

I think I have seen on housing developments that they sometimes use window templates, so the wall is built against it and a window 20mm smaller is guaranteed to fit, and can be ordered early.

This works best with standard size, multiple windows of course.

 

On our project, the kit part was built with care to the squareness and dims, and that didn't look difficult to me.  Where fitting into granite openings it was much more difficult to even measure. Some stone had to be nibbled off.

 

[JohnMo]

Our window fixing details were by our structural engineer, and as such part of our structural design certificate - but we are on a windy exposed site with larger than a normal house windows.  Window installer details were slightly different, but they went back to our structural engineer to get their details approved prior to starting work.

[Alan Ambrose]

>>> opening -50mm on timber frame and then box out using 12 or 18mm exterior ply and you can create a very good airtight box to the correct depth. 

 

I've never done this before, but that doesn't stop me having an opinion .  I was planning to use the ply box method, like PeterW.

 

And I wouldn't expect any architect / engineer to specify this unless it was some huge / custom / crazy / innovative thing.

[low_and_there]

On 23/03/2023 at 16:58, Alan Ambrose said:

>>> opening -50mm on timber frame and then box out using 12 or 18mm exterior ply and you can create a very good airtight box to the correct depth. 

 

I've never done this before, but that doesn't stop me having an opinion .  I was planning to use the ply box method, like PeterW.

 

And I wouldn't expect any architect / engineer to specify this unless it was some huge / custom / crazy / innovative thing.

 

This box ply method sounds interesting - we're having our windows fitted a couple of months after our timber (dormer) frame is put in - do you have any further detail on this approach?

[Dave Jones]

surely the window manufacturer not the supplier species how they should be  fixed ?

 

forget the architect they would draw them upside down and never know.

[Dave Jones]

On 23/03/2023 at 12:30, saveasteading said:

I think I have seen on housing developments that they sometimes use window templates, so the wall is built against it and a window 20mm smaller is guaranteed to fit, and can be ordered early.

This works best with standard size, multiple windows of course.

 

On our project, the kit part was built with care to the squareness and dims, and that didn't look difficult to me.  Where fitting into granite openings it was much more difficult to even measure. Some stone had to be nibbled off.

 

 

yes they are subframes/cavity closers. I used them on last build. They are tied into the brick course and come pre-braced square. You can order the windows while at DPC level without an issue.

[mike2016]

8 hours ago, Dave Jones said:

surely the window manufacturer not the supplier species how they should be  fixed ?

 

forget the architect they would draw them upside down and never know.

You would think!! I'd be happy with either the manufacturer or supplier but saying it must be the Architect was very strange. Anyway, am looking at using Oknoplast and have had a good chat their their rep and supplied a sample of multitherm plus.