How do I fit insulation boards?

[Tim84]

Sounds like a stupid question, however, I'm going to use 50mm Kingspan/Celotex/Recticel to insulate a T&G 19mm tannalised shed. I plan to fit it between the 3" x 2" framework then fix OSB3 on top.

I have never used these products before and I'm pretty poor at DIY so I'm wondering how to actually fix the polystyrene boards in place before I foil tape them and screw the OSB3 to the framework on top?

I think the 3" of the 3" x 2" is the depth looking at pictures of the shed, so I have about 25mm to play with for an air gap if I use 50mm board. This makes me even more confused as to how I fix the polystyrene boards in place when I have 25mm of nothing to fix it to!

Shed arrives a week tomorrow and I want to get cracking ASAP so any advice welcome!

 

[tony1851]

Are you using the polystyrene or kingspan?

Generally you just friction-fit them (ie cut the same width a the gap). If you end up a little narrow in places, use fill-and-fix foam.

 

[Tim84]

Are you using the polystyrene or kingspan?

Generally you just friction-fit them (ie cut the same width a the gap). If you end up a little narrow in places, use fill-and-fix foam.

Foil backed/fronted polystyrene, I thought Kingspan was in this category but obviously not! I was looking at Recticel from Jewsons anyway but hoping to find something a bit cheaper. I think this is basically polystyrene with foil on each side?

Friction fit it is then, I thought there may be something more sophisticated I needed to do! Is the fill-and-fix foam specific to the poly insulation boards?

 

[tony1851]

Is the fill-and-fix foam specific to the poly insulation boards?

No - use it for anything really.

Another trick is to tap nails partly into the studs, 2" back from the face, just to form a stop as you gently push the boards upto them. 3 or 4 nails down each side would be enough.

 

[Tim84]

Another trick is to tap nails partly into the studs, 2" back from the face, just to form a stop as you gently push the boards upto them. 3 or 4 nails down each side would be enough.

Good idea on the nails, would make it easier if my cutting is off (as it likely will be!)

How about cable runs for sockets, run the twin and earth 2.5mm through the air gap along the floor and then just poke it through the insulation to get it to each surface mounted socket?

 

[tony1851]

If putting cable behind and through the insulation board, don't even consider using polystyrene - it attacks the pvc coating on the cable.

I think you are OK with the PIR/PUR (yellow) boards in this regard, but hopefully some sparks will correct me if I'm wrong.

 

[Tim84]

Random, wouldn't expect that.

I guess I could run conduit behind and through the boards to protect the cable as I'll be running Cat6 cable too. Depends if my boards I get are PIR/PUR (Recticel are IIRC)

I might put a separate post in the relevant section so some electricians can advise as you suggest as this thread title won't attract their attention!

 

[ban-all-sheds]

Random, wouldn't expect that.

//www.diynot.com/forums/viewtopic.php?t=134950&start=0

I guess I could run conduit behind and through the boards to protect the cable as I'll be running Cat6 cable too. Depends if my boards I get are PIR/PUR (Recticel are IIRC)

That's probably Installation Reference Method A, so don't forget to de-rate the cables appropriately.

How are you supplying the shed with electricity? Will it be notifiable?

Sounds like a stupid question, however, I'm going to use 50mm Kingspan/Celotex/Recticel to insulate a T&G 19mm tannalised shed. I plan to fit it between the 3" x 2" framework then fix OSB3 on top.

What about the floor and roof? Not much point doing the walls and not those too.

I think the 3" of the 3" x 2" is the depth looking at pictures of the shed, so I have about 25mm to play with for an air gap if I use 50mm board. This makes me even more confused as to how I fix the polystyrene boards in place when I have 25mm of nothing to fix it to!

No breathable membrane?

http://www.ukworkshop.co.uk/forums/shed-insulation-t57971.html

 

[Tim84]

Random, wouldn't expect that.

//www.diynot.com/forums/viewtopic.php?t=134950&start=0

I guess I could run conduit behind and through the boards to protect the cable as I'll be running Cat6 cable too. Depends if my boards I get are PIR/PUR (Recticel are IIRC)

That's probably Installation Reference Method A, so don't forget to de-rate the cables appropriately.

How are you supplying the shed with electricity? Will it be notifiable?

Sounds like a stupid question, however, I'm going to use 50mm Kingspan/Celotex/Recticel to insulate a T&G 19mm tannalised shed. I plan to fit it between the 3" x 2" framework then fix OSB3 on top.

What about the floor and roof? Not much point doing the walls and not those too.

I think the 3" of the 3" x 2" is the depth looking at pictures of the shed, so I have about 25mm to play with for an air gap if I use 50mm board. This makes me even more confused as to how I fix the polystyrene boards in place when I have 25mm of nothing to fix it to!

No breathable membrane?

http://www.ukworkshop.co.uk/forums/shed-insulation-t57971.html[/QUOTE]

Hi ban-all sheds, topical name!

- I'll look up installation reference method A, thanks, as I know nothing about this or 'de-rating' the cabling

- supply to the shed will be SWA cable run externally from the main consumer unit and into a garage consumer unit mounted on the OSB3 lining. This will be done by a Part P certified electrician

- roof and floors will be exactly the same, 50mm Recticel and OSB3. The only difference being there will be no air gap on the floor

- hadn't planned on a breathable membrane as I thought the 25mm gap alone would be OK, do you suggest otherwise?

 

[ban-all-sheds]

Hi ban-all sheds, topical name!

not

- I'll look up installation reference method A, thanks, as I know nothing about this or 'de-rating' the cabling

This is out of date, but the principles remain the same:

http://www.tlc-direct.co.uk/Book/4.3.3.htm

However....

- supply to the shed will be SWA cable run externally from the main consumer unit and into a garage consumer unit mounted on the OSB3 lining. This will be done by a Part P certified electrician

...the electrician needs to certify all the final circuits, so he needs to choose and install the cables.

- hadn't planned on a breathable membrane as I thought the 25mm gap alone would be OK, do you suggest otherwise?

AFAICT there's no firm opinion one way or the other. On balance it's probably better to have one and not need it than the other way around, but search here, and ask the question, and also look at other fora, like the one I linked to above, and here.

More thoughts here: http://www.shedblog.co.uk/sf-forum/just-shed-talk/shed-insulation-and-heating-question/