Adding Insulation to Metal Shed

[mike2016]

I've a new metal shed installed this week and want to look at installing some insulation. It's a lean to roof style with felt under the roof and holes at the back. The rest is sealed, I'm just waiting on windows to be fitted. I was thinking of 40-50mm rigid foam insulation on the floor and walls, OSB on top of this for the floor and osb/plywood on the walls.

 

It's the roof I'm concerned about. Should I put in some type of vent system to ensure breath-ability to the outside? Ply on top of this to keep the weight down as I don't want it sagging might be best? I plan to fix the osb/ply to the 40mm box steel to secure it over the insulation. Also build a timber box around each window opening inside the insulation layer.

 

I'll pre wire it for lights and sockets - is it ok to run 2.5mm wire between the insulation and the outside metal panel or should it be kept inside the thermal envelope with steel or plastic trunking? I want to store things in here year round and not worry about mould / damp etc. 

 

Any advice appreciated! Thanks.

 

[Nickfromwales]

Leave all the fillers out and just foam / bond EPS insulation to the high points. That'll allow air to shift behind the insulation and keep condensation in the middle from being so problematic.  Buy some sticky neoprene 50mm x 3mm insulation 'tape' and do the 3 sides visible of that 40?mm box steel, as that'll be your biggest cold bridge from outside to in, doubling up on the very inside face(s) only. Foam all of the corners and make it draught-proof as best as you can, but still maintaining clear open ends for the sheet profiles. 

Them being mounted horizontally makes this airflow a bit less 'natural', but shouldn't be a problem.

Use foam / other suitable bonding agent and hold the sheets of EPS in place with 8x4's and some temporary battens, like shuttering. Try not to let what you store touch the outside walls and that will promote better mould prevention, but ironically you'll probably need to have some ventilation there in the summer to stop it sweating.

Have you insulated under the floor yet? If not, you'll need to address the junction where the walls meet the floor as that'll be the biggest problem area if left unaddressed. Foam will be your friend here, just choose low expansion grade and minimise the wastage / nuisance contamination from over expansion.

I don't really see the point in going to the expense of PIR tbh. EPS is pennies by comparison,.

Edited July 9, 2020 by Nickfromwales

[mike2016]

Neoprene on!

 

So I got plywood as the internal finish. I'll paint the walls and ceiling but how should I treat/paint the 12mm hardwood faced plywood floor (on top of 30mm XPS in this case)? Use a decking treatment? Thanks!

[Nickfromwales]

8 minutes ago, mike2016 said:

Neoprene on!

 

So I got plywood as the internal finish. I'll paint the walls and ceiling but how should I treat/paint the 12mm hardwood faced plywood floor (on top of 30mm XPS in this case)? Use a decking treatment? Thanks!

I used garage floor paint. Hard wearing and just nice to look at ( grey not terracotta )and cheap as chips. Also, it should act like a bit of a vapour barrier too. Moot most likely, but made sense to me and my small grey nodule.

Takes a LONG time to dry so put on in lots of thin layers.

Edited July 29, 2020 by Nickfromwales

[mike2016]

Got some of that paint for the floor and blinds for the windows. Started out on the floor and got help from a friend for the ceiling which was awkward. Walls are next.....!! Thanks all.