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Act VI - Scene II - The Consequences of Space


AliMcLeod

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Based on our brief, our architect had taken the original designs that came with our plot, utilised the same house footprint, and had come up with a new set of designs and internal floor layouts.

 

We had two choices for the external design - a flat roof or two mono-pitched roofs. After a little discussion between my wife and I, and with to the architect, we agreed on the two mono-pitched roofs design.

 

The house to the west of us had an almost flat roof (they initially submitted plans for a flat roof, but the planners insisted on a 5 degree gradient), and the proposed one to the east had the same plans as those that came with our plot, albeit a little smaller, with a mono-pitched and a dual pitched roof, with dormers. We spoken to the owners of the house to the west, and they said that planners were adamant that they could not have a flat roof. We felt we'd get the same decision if we wanted to go down that route, but we also felt that the two-mono pitched roofs would add a bit more character to the house and fitted in better with the overall streetscape.


So, this was our new house design.

 

option2.PNG.2ef789f1dba51c33402f7e1469195b31.PNG

 

 

 

Now, this seems obvious to me now, but what I hadn't quite realised at the time how much roof layout of the the original design had reduced the internal foor space of the house. After we'd made the decision to go with the two mono-pitched design, we let our builder know and asked for an updated cost plan.

 

As part of our brief to the architect, we'd also reminded him that we lived in Scotland, so probably didn't need there balconies, so this was reduced to one. This was bound to save costs, we thought, and made sure our builder took that into account.

 

However, our builder soon got back to us asking if we'd realised that the new roof design had increased our floorspace from around 250 m² to around 340m² and, even with the simpler roofs, and the removal of the balconies, that would therefore increase the build cost. The change had also increased the ceiling heights from 2.4 meters on each level (from the bottom up) to 2.5m, 2.675m and 2.5 meters. Finally, he pointed out that the change of slope on the roofs to under 20 degrees meant that we could not longer use slate for our roof and would have to either use a membrane or aluminium zinc, with the resulting additional costs.

 

Overall, the above increased our build estimated cost by around 20%, including a doubling of the cost of the roof (it would also mean changing soffits, fascia, downpipes etc).

 

That amount was starting to eat into our contingency, but was something we could afford, even if it eventually meant a little bit more on the mortgage.

 

Looking back, I do wonder whether we could/should have shrunk the house a bit at that time, saving some costs but still having a house that would still be big enough for our needs - we don't need that space day-on-day but do have family visiting from London and Dublin a few times a year. And, more space is good, right? 

 

I've been happy with our architect, but the changes to the house design, and in particular the reduction in the roof gradient precluding us from using slate, has taught me to always think about, or ask about, the potential consequences of any other proposed changes.

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I think copper or zinc would be really fitting and cool for the roof :-) 9_9 .

 

Or there are tiles that will work at 20 degrees. Not sure about slate-like tiles.

 

Ferdinand

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I said aluminium, didn't I :$ 

 

The roof is actually going to be Zinc (I do love the look of that material) - its the downpipes and guttering that might be aluminium. Fixed above.

 

Our roofs are around 10-12 degrees (from memory) - each roof is slightly different

Edited by AliMcLeod
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I guess to save money you could go box section corrugated, but I would not be totally sure of that by the sea.

 

Personally I am a sucker for copper.

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You can get a single ply membrane flat roof and a PVC profile which is stuck onto the roof to make it look like a metal standing seam roof which works out a huge amount cheaper. It's incredibly hard to tell the difference when it's on a single story roof and on a taller building like yours you'll never know. We installed it on a school in the west of Ireland facing the wild atlantic and it's holding up very well so wouldn't worry about durability.

 

eg of a product 'Sika Decor Profile SE' and example pictures I found on Google.

 

Sika-Sarnafil-single-ply-roofing.jpg

 

Sika_Sarnafil_Roof_Essex.jpg

 

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@Dudda Thanks for that - it looks good. Do you know roughly what that cost per m2?

Edited by AliMcLeod
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4 minutes ago, AliMcLeod said:

@Dudda Thanks for that - it looks good. Do you know roughly what that cost per m2?

The cost is determined by the quality of the membrane you use. The stick on PVC profiles come in 3 meter lengths are very cheap. You just have to take the time and make sure there stuck on straight.

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I think once you starting looking closely at standing seam roofs, you'll not feel that a single ply membrane would look the same. While it's a good, long lasting product and very good value, I personally feel that they are very noticeably not a metal roof. 

 

We ended up going with Aluminium.

 

Started looking at Zinc, but didn't actually want the natural colour of Zinc so looked at coated versions. Pricing was £100 - £120 sqr. m. and  a few concerns about longevity if you don't get the ventilation gap right underneath. ie. any condensation on the underside will rot Zinc very quickly. We were told by a Zinc roof installer of a Zinc roof with corrosion perforation within 7 years due to blocked vent gaps on a warm roof. 

 

At one point Colourcoat Urban (steel) seemed very cost effective, and I was willing to accept a less traditional flashing around the roof lights to get the significant cost save, but when I came to actually order the costs rose significantly (not sure why) from when I had initially costed it and the pricing ended up slightly higher than Aluminium.

 

For me the coated Aluminium gives a near identical look to (coated) Zinc, at better value and is more durable. As it's ductile all the flashing and joining can be done by traditional hand-formed methods so you get the idiosyncrasies of a Zinc or Copper roof.

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Thanks @IanR How did the aluminium price compare to the Zinc? Our neigbhour to the west used a membrane, but their roof is around 5 degree so the only place you can really see the roof is from the back of their (and our) garden.

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Mines a relatively simple roof, 15 degrees and no dormers (but a few roof lights), and a large area so I expect (hope) the price I paid will be at the lower end of an average domestic roof. Ours worked out at a little under £55 per sqr. m. (not including OSB substrate)

 

Another thought: I'm not sure what the options are for fixing items like solar panels to a single ply membrane roof, if that's a consideration. With a metal standing seam roof you can fix to the standing seam with standard clamping brackets.

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25 minutes ago, IanR said:

I think once you starting looking closely at standing seam roofs, you'll not feel that a single ply membrane would look the same.

I agree a metal one will always look better but when will you be 'looking closely at standing seam roofs' when in this example its 5 meters off the ground and you'll have to be standing back another 10-15 meters from the house to see them due to the low pitch?

The house is also very elevated on a steep slope so on the road you’ll be even further away and it doesn’t look like the roof is overlooked by anyone. Looking at the above elevations the closest to the ground is the north elevation which is also the rear. 


If you’ve the money go for the metal but if not the membrane is a very good compromise where you can't see it up close.

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1 hour ago, IanR said:

I think once you starting looking closely at standing seam roofs, you'll not feel that a single ply membrane would look the same. While it's a good, long lasting product and very good value, I personally feel that they are very noticeably not a metal roof. 

 

We ended up going with Aluminium.

 

Started looking at Zinc, but didn't actually want the natural colour of Zinc so looked at coated versions. Pricing was £100 - £120 sqr. m. and  a few concerns about longevity if you don't get the ventilation gap right underneath. ie. any condensation on the underside will rot Zinc very quickly. We were told by a Zinc roof installer of a Zinc roof with corrosion perforation within 7 years due to blocked vent gaps on a warm roof. 

 

At one point Colourcoat Urban (steel) seemed very cost effective, and I was willing to accept a less traditional flashing around the roof lights to get the significant cost save, but when I came to actually order the costs rose significantly (not sure why) from when I had initially costed it and the pricing ended up slightly higher than Aluminium.

 

For me the coated Aluminium gives a near identical look to (coated) Zinc, at better value and is more durable. As it's ductile all the flashing and joining can be done by traditional hand-formed methods so you get the idiosyncrasies of a Zinc or Copper roof.

 

Hi Ian, which aluminium system did you use? We're still intending to use colorcoat urban but frankly their technical backup has proved appalling. I've been waiting weeks for an answer from their technical team but after numerous chases I'm ready to throw in the towel. 

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We went with Falzonal from Novellis. I believe the UK Distributers are:

http://www.raaltd.com/falzonal-prepainted-roofing-coil.html

 

I don't know that they are the only distributors, but that's who my installers bought it in from.

 

I'm avoiding giving out the details for my installers, They did a good job, but deceived constantly with regards timing. Initially promised the timing I was after so that they got the job, but then just gave me constant BS about why it was everyone else's fault they were unable to start. Started 6 weeks late in the end and then took 8 weeks to complete a 3 week job, as they were running other jobs at the same time.

 

RAA may be able to suggest installers. If you go that route, send me a pm and I'll let you know who did mine so that you are pre-warned.

 

Out of interest, what's the cost per m2 you are getting for the Colourcoat?

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1 hour ago, IanR said:

We went with Falzonal from Novellis. I believe the UK Distributers are:

http://www.raaltd.com/falzonal-prepainted-roofing-coil.html

 

I don't know that they are the only distributors, but that's who my installers bought it in from.

 

I'm avoiding giving out the details for my installers, They did a good job, but deceived constantly with regards timing. Initially promised the timing I was after so that they got the job, but then just gave me constant BS about why it was everyone else's fault they were unable to start. Started 6 weeks late in the end and then took 8 weeks to complete a 3 week job, as they were running other jobs at the same time.

 

RAA may be able to suggest installers. If you go that route, send me a pm and I'll let you know who did mine so that you are pre-warned.

 

Out of interest, what's the cost per m2 you are getting for the Colourcoat?

 

Roughly £55 m2.

the Falzonal distro came back instantly with just one supplier name. Just about to PM you :).

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On 4/6/2017 at 09:59, Dudda said:

You can get a single ply membrane flat roof and a PVC profile which is stuck onto the roof to make it look like a metal standing seam roof which works out a huge amount cheaper. It's incredibly hard to tell the difference when it's on a single story roof and on a taller building like yours you'll never know. We installed it on a school in the west of Ireland facing the wild atlantic and it's holding up very well so wouldn't worry about durability.

@Dudda

I agree with you completely!

If you pick the right system and use that stick on profile that you mentioned its extremely difficult to tell the difference between the single ply membrane and metal. I've specified roofing like that several times near the coast where metal corrosion would be problem and also inner city areas where metal theft is an issue.

Also, metal roofs can sometimes lead to problems with noise transfer into the building from rain drumming on the roof.

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