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Batten fixings through PIR


Pocster

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Hey all!

 

Looking into the next stage of cladding the rear of the property with larch.

My architect wants 100mm sir insulation then vertical battons (with presumably horizontal on that for ventilation ).

So I have to fix the batten through 100mm PIR into the timber frame ; is https://www.twistfix.co.uk/twist-nails the type of thing I should be using?

It seems like a lot of weight (once fully clad) hanging 100mm out from the timber frame (I'd be happier if the batten was tight to the timber frame - but this I guess isn't allowed).

Also with the larch; how do I finished around windows/doorways? ; can you buy special 'trim' for that?

 

Cheers

 

 

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Hmmm, The more I look into this the less happy I am!

Really I want to batten straight onto the timber frame - much stronger! ; but the architect didn't want any thermal bridging!

Could I not do this; infill with PIR ; then fix horizontal battens to the vertical battons and PIR infill them (i.e. 2 lots of 50mm PIR).

More work; but surely much stronger!; doesn't require any special fixings either (twistfix/helical etc. always expensive!)

 

If I make the final horizontal battons thicker than 50mm then that will also leave a gap for airflow under the cladding.

 

Just thinking (typing!) out loud - any opinions on this before I commit (i.e. spend!)

Though I guess technically there would be a thermal bridge where batten crosses batten ..... though I could cut a small piece of PIR to cover that.

Edited by pocster
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2 minutes ago, Mr Punter said:

Use 50mm pir and perhaps insulated plasterboard?

Yeah I could 'thin' it out. I'm going to have PIR inside wall cavities aswell anyway.

Just really trying for 100mm external with no thermal bridging and rock solid strength fixing.

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27 minutes ago, pocster said:

Yes but it is a very good cold bridge! I have the same issue and had not arrived at a final solution but I did look at the structural issues a bit. Essentially once the batten is pulled tight against the insulation the friction helps carry the load BUT you have to crush the PIR which means the grip is variable so I dismissed that one. Standing the base of the batten on something helps but moisture might be an issue. In the end my preferred solution was to going to be to make hundreds of plastic bushes, a fraction shorter than the PIR thickness, about 30mm in diameter with an 8mm hole. These would go in holes in the PIR directly onto the timber frame and the screw pass through the batten through the bush into the Timber frame and when pulled in tight would slightly crush the PIR but be held a fixed distance from the frame by the bush and supported off the frame by it. Will draw a picture when I get home.

Edited by MikeSharp01
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18 minutes ago, Crofter said:

Fit an external layer of osb over the PIR, then the battens go onto that (fixed right through to frame) Will add mucho stiffness.

What I don't like is it's all hanging 100mm off the structure .

those brackets might create a thermal bridge ; but worse than timber on timber ?

i remember a similar issue with my brackets holding up the external blockwork . Solution was some special I.e expensive low thermal conductivity plastic that sat between the bracket and the fixed structure.

 

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I think @NSS used it.

I briefly looked into it myself but it was considerably more expensive than the locally grown larch that I ended up with. Has many advantages, though. I think you may have to drill all the fixing holes rather than nail gunning it on.

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10 minutes ago, Crofter said:

I think @NSS used it.

I briefly looked into it myself but it was considerably more expensive than the locally grown larch that I ended up with. Has many advantages, though. I think you may have to drill all the fixing holes rather than nail gunning it on.

Yeah I might look into it a bit more ...

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1 hour ago, pocster said:

Yeah I might look into it a bit more ...

I used a mix of Thermowood and Marley Cedral Click. The latter is tongue and groove fibre reinforced cement board with invisible fixings. 

IMG_20170908_1609151.jpg

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Use the twistfix/helical fixing as that's what they're designed for. It's by far the best job. I've used helical screws on a few different projects going through pir insulation. The first time they were on a very steep roof holding up the huge weight of very thick blue Bangor slates on a church refurbishment. I was a bit worried as it was a 150 year old timber structure but the helical company did calculations and gave me the length and spacing to be used. It all worked out great and I've used them several times since on other projects.

 

Talk to the company and get them to work out the calculations of how many are needed and what length. This will hopefully put you at ease. It's more that strong enough. Remember timber cladding with hold it all together unlike the blue Bangor I used. 

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10 hours ago, NSS said:

I used a mix of Thermowood and Marley Cedral Click. The latter is tongue and groove fibre reinforced cement board with invisible fixings. 

IMG_20170908_1609151.jpg

That looks very sharp!

 

Did you install the cladding yourself? 

 

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1 minute ago, pocster said:

That looks very sharp!

 

Did you install the cladding yourself? 

 

I did, with a little help from a couple of mates. The Cedral Click comes in 3.6m lengths and is pretty heavy so needs at least two pairs of hands to lift and slot into place, particularly on the higher level stuff on the gable ends.

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57 minutes ago, NSS said:

I did, with a little help from a couple of mates. The Cedral Click comes in 3.6m lengths and is pretty heavy so needs at least two pairs of hands to lift and slot into place, particularly on the higher level stuff on the gable ends.

Fantastic !

ill be doing it on my own as usual as I don’t have any mates ! :/)

the window returns and trims - were they easy enough ??

 

cheers 

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Marley Cedral Lap in light oak, I’d have preferred the T&G Click system but they don’t do it in the wood effect colours. (Something to do with the paint not taking to the edge of the board or something - never made sense to me)

 

Really happy with the Lap regardless, from a distance I’m not sure you can tell it isn’t T&G

A6996A0E-77D0-4473-8A5E-1D0A34FF4D1D.jpeg

DF440F1F-7C0D-40AD-A85E-6ACF9D604AC2.jpeg

Edited by Grosey
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4 hours ago, pocster said:

Fantastic !

ill be doing it on my own as usual as I don’t have any mates ! :/)

the window returns and trims - were they easy enough ??

 

cheers 

Yep, but you need to be careful with the vertical trims for the window reveals to ensure a good fit of the 'lintel' profiles that then carry the board immediately above the windows. We used offcuts to do a temporary build up either side of each window to make sure we got it right as the corner profile on the reveal sides has to be fixed before the boards go up. We're using Marley Opera board (same colour and material as the Click) to complete the inside face of the reveals.

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39 minutes ago, NSS said:

Yep, but you need to be careful with the vertical trims for the window reveals to ensure a good fit of the 'lintel' profiles that then carry the board immediately above the windows. We used offcuts to do a temporary build up either side of each window to make sure we got it right as the corner profile on the reveal sides has to be fixed before the boards go up. We're using Marley Opera board (same colour and material as the Click) to complete the inside face of the reveals.

Right. So the opera board is just for the returns?.

I've got no glazing in yet; so not sure whether I should fix before or after......

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2 hours ago, pocster said:

Right. So the opera board is just for the returns?.

I've got no glazing in yet; so not sure whether I should fix before or after......

Definitely after. If you zoom in on the nearest window in this pic you'll see that the operal board is not yet in but we set the corner profiles so that the board will sit against the frame and then I'll seal around with clear silicon.

IMG_20170908_1609072.jpg

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