How to insulate a shed on a budget

[smiley65]

Hi everyone,i have bought a 12x8 shed to use as a hobby workshop and need to insulate it as i use electrics in there for the electrics i run 2 extension leads out to the shed as needed,i have painted the outside of shed with ronseal paint to protect against the weather but need to insulate the inside as cheaply as possible as only have disability money to achieve the end result.the shed is tongue and groove and the framing is aprox 60mm thick i was hoping to use 50mm polystyrene from bq and put some 10mm battens down each side of frame to leave a 10mm gap between outside t&g and insulation then 6mm ply over the top marking all studs as i go so i know for future use,does that sound ok?

 

[Rorschach]

Get some 50mm kingspan or similar. You can buy it second hand which will be plenty good enough for a shed.

 

[smiley65]

looked at that and it was to expensive for me even looked at ebay for seconds

 

[colinc]

Hi,

Polystyrene is not as efficient as Celotex and similar, but is cheaper. I would check out prices at local builders merchants though. They will almost certainly be cheaper than B&Q.

Do the floor too if you can.

Colin

 

[MikeG.]

Terrible stuff, polystyrene. At the very least, make sure it isn't the version which turns into napalm in a fire. You'll find that the most expensive part of your plan is the 6mm ply, not the polystyrene.

 

[Rorschach]

I wouldn't waste my time with polystyrene, the effort involved will negate any benefit. It can also wick moisture which is not good in a shed and has no vapour or radiant barrier.

Pay the extra for decent stuff.

 

[Fitzroy]

I often see offcuts of celotex/kingspan on gumtree round me for free/cheap. You’ll have to patchwork the fitting but for a 12x8 shed a you may be able to scrape together enough. Depends on just how much of s budget you find yourself.

F.

 

[avengerwrc]

I think you need to answer the question, do I want to insulate this shed ? if yes then you need to do ALL of it, the walls and the roof. You are going to make an insulated box. Do this correctly and your tools will be dry and very little heat will be required to ensure no condensation. Buy cheap loft insulation and run these between the studs, cover the whole lot with cheap plastic sheeting, fix with a staple gun. Then get reclaimed 18mm sheets. Screw these to the studs, you can then fix anything directly to the walls. Do the same with the pitched roof but use 6mm ply. Oh, don't forget the back of the door too and double glaze any windows. For the floor cover in hardboard, easy to clean. My shed is 22ft by 10ft and it costs pence to heat, there is no condensation.
Colin.

 

[smiley65]

Thanks for all replys,i did think of using loft insulation but was told i needed to have a gap between it and the walls of the shed, and yes was going to insulate the roof as well and the door,so do i need to have a gap between the insulation and outside walls?the floor was going have 18mm osb painted with some kind of moisture sealer on it, as i really have to do on a budget all ideas are welcome

 

[MikeG.]

Yes, you absolutely must have a gap between the insulation and the inside of the cladding boards. 25mm, at least. This means you have to get something in there to hold mineral wool-type insulation away from the boards. This is one of the principle reasons I don't advocate people buying pre-made sheds as a workshop.

 

[smiley65]

Health reasons dictated i bought a shed pre made and installed, i understand your reasons but sadly not a choice sometimes,i dont think loft insulation is the way to go then with the gap needed looks like it may well be foil bubble wrap with ply over the top

 

[MikeG.]

Those "thinsulates" aren't that thin (because of what I am about to tell you), and may not be the answer. They need a 25mm gap both sides to work, so actually occupy about 60mm in depth.

 

[sunnybob]

Papier mache egg trays.
If you can find any they are absolutely magnificent for insulation and sound deadening. Nail them to the wall, overlap the next to cover the edges. by the time you have three layers youre getting toasty.

Downside is they tend to collect a lot of dust, but as long as you dont disturb it...

 

[Geoff_S]

Why do you need a gap when using loft insulation?

The reason I ask is that I used loft insulation in my shed, 20 years later I see no problems. Now I'm worried

 

[sunnybob]

some insulation materials absorb and retain water. If its laying against a thin outside wall it will get damp and stay damp, slowly spreading inwards.

 

[Geoff_S]

I found this on the Rockwool site.

"ROCKWOOL insulation is moisture resistant yet vapor permeable. ... ROCKWOOL stone wool insulation does not wick water, which means that any bulk water that contacts the outer surface will drain and not be absorbed into the body of the insulation."

So I'm safe?

 

[Marineboy]

I’m no expert (need to wait for MikeG to come along), the question to ask is...where does that water go? It will drain to the bottom of the cavity and rot the sole plate and any other timbers it contacts. You have to prevent water or water vapour getting in and/or provide sufficient air gap to allow moisture to evaporate.

 

[sunnybob]

Its not relevant to a timber shed very much, but I had rockwool cavity insulation fitted to a house way back in 1978. It was magnificent as an insulator. I stayed in that house for 14 years and never once regretted having it done.

 

[smiley65]

It has been suggested that i line the inside of shed with builders paper moisture barrier as i was going to do, then use foil wrapped bubble wrap as it effective as 55mm polystyren any thoughts?

 

[Rorschach]

How thick is the bubble wrap? If it's just standard reflectix you are wasting your time.