Shed insulation

Hi

Im having a new metal shed anyone got ideas about wall insulation.

Im thinking something like 25 mm kingspan with a plywood or white melamine inner face on 25x50 studs stuck to shed walls with structural silicone

100mm works well. Maybe you needed a bigger shed?🙂

Peter. some years ago when i was rebuilding Insurance write off motorcycles & scooters for a hobby, i ran out of storage space. So i bought a 10 foot by 8 foot steel shed. The condensation was really bad. So i purchased from the Builders yard Insulation panels with foil on one side. I adhered these to the whole interior of the shed including the doors. I even foil taped the joints. These were 50mm thick.

The result was not good & it still was always soaking wet. If you have already ordered it, or are sure it is what you want then i would strongly consider doing spray foam insulation. I think the problems with my shed was it as i guess they all are the profile is either curved or castle wall corrugated steel. So when insulated there is no contact on the high point of the corrugation. That is where the problem is.

If you spray foam it then i am sure it will be fine. This is how i built my new steel garage/ workshop.

Steve.

Edited By Steviegtr on 06/03/2022 23:21:16

Unless you use the premade sandwich panels sealed with metal on the inside too, ie 100% waterproof you will get condensation on the inside of the metal. You then have to follow 'cold roof' techniques. That is try and stop the moisture from the inside migrating out using a vapour barrier but then have a well ventilated gap on the inside of the outer metal shell so that it doesn't sit there and make the insulation wet.

The ventilated gap does work well

Note this is ventilation for the inside surface of the metal skin only NOT the whole shed. If possible use plastic sheet to make the inside surface of the insulation as airtight as possible and use a dehumidifier to remove the moisture you breathe out.

25mm polystyrene works very well. Going thicker is obviously better but uses up a surprising amount of space for a relatively modest gain.

Neil

Where I used to work we had a wriggly tin storage shed, a huge thing, no heating, and very infrequent human occupancy. Everything inside got dripping wet, condensation on the inside surface of the corrugated iron dripping off. This happens because on a clear night the steel gets colder than the air and water from the air condenses, both inside and out. The only way to stop it on the inside is to keep the air away from the steel. As others have said either premade sandwich or spray foam

Wooden shed cocooned in roofing felt, keeps rain off wooden planks. Recycled 3ply fixed to inside of shed frame walls and voids stuffed tightly with mineral wool intended as loft insulation. Even did the door by glueing and screwing on a frame around the edges in addition to the usual Z frame, followed by glue n screw 3 ply and stuff voids with mineral wool. Polystyrene panels 2" thick glued inside roof between the frames. Finally glueing on scrap lumps of polystyrene to cover the joints, rather than tape. If I ever move and leave the old apex roof shed behind, I'll have a flat, pent roof next shed - easier to do the roof insulation.

Keep it loose, it is the trapped air in it that does the business.

It might be an idea to drill a few small (circa 12 mm ) holes right at the bottom of the outer steel walls to allow damp air/ moisture to exit. (Problems with damp church walls are solved by inserting unglazed clay pipes low down in the walls, and sloping downwards toward the outside )

Insulate roof as well as walls, and floor if possible.

If it is any help, with ideas, a description of my shop follows.

My shop is wood clad / framed, built in late 2003, is 10'9" x 6' 9" external, 8' feet high at front, 7'6" at rear. ..

19 mm cladding T & G outside, on 50 mm frames 12 mm ply inside. the void is filled with glassfibre insulation. The door, being a fire door is in a 100 mm framed wall. The roof is 50 mm frame, with 12 mm inner and outer cladding, insulated with glass fibre. Originally felt covered but now one piece sheet rubber.

The floor is 18 mm ply, sitting on 8" x 2" bearers, and enclosed on front and back end, to just about floor level.

Tall fence close to the back wall

The door end is bout 2 metres from the house wall, so fairly well protected .

There is a hooded, fixed vent, high on the back wall, containing an intake fan (Rarely needed ) and two smaller ones at floor level. Often I work with the door open, for light as much as for ventilation.

No windows (Space needed for shelving! )

No condensation troubles, rust virtually unknown.

With the door closed,a 2 Kw fan heater usually warms it up in about 15 minutes and then then runs for about 10 minutes each hour to maintain about 18'C.

Location UK, East Anglia, so temperatures below freezing are fairly rare.

Howard

I bought 50 mm kingspan sheets 8x4 seconds worked out about a third of the price new. Delivery from wales cost me £30. Plenty of companies advertising on line.

The vapour barrier must be inside the insulation, or moisture from the inside will migrate out and condense on the outer skin wetting the insulation and rendering it useless. An air gap is needed between the insulation and outer skin to dry it out. In building my workshop I followed timber building pracrise

from the outside

plastic cladding on 25 mm laths with vents top and bottom

breathable building paper

10 mm obs on 4*2 studding

kingspan insulation

vapour Barrier

12mm vertical flooring chipboard for inner wall

bone dry, warm and never any rust