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Window position within cavity?


Shanemac

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Hi, I'm hoping someone can express an opinion on the position that our windows have been fitted.

 

The fitters have direct fixed the 80mm deep ali frames to the external block leaf (flush with the cavity side and approx 15 - 20mm back from the outside) 

 

We have a mix of timber cladding and render going on.

 

So, is this correct? Since they were fitted several trades have commented that they're set quite far out, rendering will be a nightmare and they're likely to leak?

 

Further research suggests there will be a bad cold bridge and possibly condensation issues, or are they fine?

 

Would appreciate any input.

 

Many thanks20230911_184631.thumb.jpg.b2a86ba9329d2de1845d15ac51c7db77.jpg20230911_184829.thumb.jpg.a60dbf1542818122f61249dbfee966fb.jpg

 

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Thanks for your reply. 

I thought I'd read that re building regs but couldn't find it again or in the part L documents?

 

So they should have been fitted on straps then? It's a 150 cavity.

 

Stub cills fitted, slate cills will be fitted underneath. 

 

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It was One of the accredited details. Labc, Nhbc, Bre, all now thrown in the bin since the new part L1 came into force. Now saps has to use psi values, or accredited thermal modelling. You did a good job spotting that that is a hideous thermal bridge. Get them back, and get them to sort it.

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I put the question to them last Friday and they came back to me today after speaking to the fitters (their own in house) and their reply was our builders told them that's how they wanted them (very unlikely, don't think they were on site at the time) but that they wouldn't cause any issues as they are.

 

I wanted to be sure I wasn't making a fuss over nothing so I'll get onto them again. 

 

They were here for 10 days fitting(quite a lot of windows) so I don't doubt they'll dig their heels in about moving them.

 

Many thanks for your help.

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No problem. Don't take any flannel from them. The fitting is not right. Does not meet the part L regs, and is a huge thermal bridge.  Warn them that they don't want to have to have a face to face chat with your mate Big Jimbo.  If there are any bodies they are members of "Chas, Trusted trader " etc i would report them. How many other windows and doors have this company fitted incorrectly in the local area. 

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9 hours ago, TonyT said:

Does the agreement/contract state they will be fitted a certain way?

just more evidence for you if you haven’t thought about that.

 

 

No nothing specifically about position within cavity, I had assumed that would be fairly standard procedure at the time. They had the details for where there was timber cladding/render etc.

 

23 minutes ago, dpmiller said:

Where exactly in the UK are you? Difficult to cite the Regs if you don't know which version...

We're in South west England.

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10 hours ago, Big Jimbo said:

No problem. Don't take any flannel from them. The fitting is not right. Does not meet the part L regs, and is a huge thermal bridge.  Warn them that they don't want to have to have a face to face chat with your mate Big Jimbo.  If there are any bodies they are members of "Chas, Trusted trader " etc i would report them. How many other windows and doors have this company fitted incorrectly in the local area. 

 

exactly this. 

 

The way they have been fitted wastes all that time an effort of having a 150 cavity. It's if you have no cavity at all. It's not a massive job to fit them correctly on straps and has already been said get 70% of the frame sitting in the cavity leaving just enough extending into the blockwork so that the frame can be weather sealed to the blockwork.

 

Do tape the insides to make sure they are airtight.

 

I'm going to take a wild guess here but the architect drawing didn't specify this detail right ?

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Good luck finding straps that work with a 150 cavity and fit your profile, I couldn't...

 

Ended up sitting them 20mm over the cavity as compromise. Better than the 30mm back from the face that the regs used to allow, but not technically compliant.

 

BCO inspected and didn't even comment...

 

The other issue, as highlighted by my builder is the poor quality of the cavity closers you get these days. Wobbly plastic things with a small flange... Good luck putting packers onto those...

Edited by HughF
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17 hours ago, Dave Jones said:

window manufacturer supplies the straps. 

 

Use built in (tied into the brick courses) closers that are ready made and braced square. have zero issues and no 'wobbles'.

Longest strap I can get for the profile from my supplier is 150mm, doesn’t span the cavity. 
 

agree on the closers though, got to be built in as you go.

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  • 4 weeks later...

An update on this, the Company acknowledge that they're not fitted correctly but are still standing by their statement that is due to the direction of my builders. (My builders issued no direction on fitting) It's getting quite heated so I won't say too much more at the moment. 

 

They do insist that the large fixed gable frames must be fixed directly to the external skin for stability and due to wind loading. (They provided a technical drawing and I fabricated a 70mm box steel which sits between the apex and lower frames) 

Does anyone know if this is correct or should it also be pulled back into the cavity?  Thanks

20231005_162306.jpg

Edited by Shanemac
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