Lining a Metal Shed

[Stuart R]

After 15 years, my garden shed has one wall full of woodworm and half the floor has been nibbled away by rodents. Time to find something different.

My local garden centre had a display of metal sheds. I'm sure it would have been cheaper to purchase an old caravan to hide at the bottom of the garden, but access would be tricky. This new shed arrived flat-packed and was assembled for me by the manufacturer.

It's been designed to be 1/3 garden storage and 2/3 hobby workshop, but it's sat here for a few months unused. I need to get it lined inside but would appreciate any tips before I start, there are quite a few threads on wooden sheds, but this is something different.

It's built on a framework of 40x40mm square, steel tubing. Clad in corrugated, plastic-coated metal sheets. The roof is similar but coated inside with a fleecy lining that collects any condensation and allows it to gently evaporate during the day, rather than collecting in drips.

At the moment condensation isn't a problem. I'm not spending any time in there and the roof corrugations leave plenty of space for the air to move around -and Autumn leaves to come in! My plan is to seal these gaps and add a lightweight ceiling, adding some insulation in-between. I'll have to ensure some extra ventilation is added, a friend suggested solar-powered boat ventilators.

The floor is 18mm OSB mounted on top of a 40x40mm box section base frame. This is standing on a bed of paving slabs laid on sand. At this point, I think I'll be told there is not enough gap under the floor to let things breathe. I would have liked to of dug out a deeper space under the shed,with maybe just brick piers to support the framework. Unfortunately the manufacturer wouldn't give any measured drawings to show the base layout.

I have to work with what I've got, so any tips on how to insulate the work area and get the best longevity out of this investment would be appreciated.

My plan is to attach some wooden battens to the steelwork and then insulate with Celotex or similar before lining with ply or plasterboard.

I was thinking of creating a false floor with more insulation (40mm?) laid on top of the original OSB, but wonder if I'd be better of raising the original floor and increasing the space above the paving slabs a bit before I start.

Should I use a vapour barrier on the walls and/or floor? Not sure how effective this would be as the walls could only be done in strips between the steelwork rather than a continuous sheet.

From reading previous shed-lining threads, I know there's a bit of experience here, so would be grateful if anyone could offer their thoughts.

Thanks in anticipation,

SR

[G6Tanuki]

Why bother with wooden battens - you can attach Celotex to the metal panels inbetween the tubing using one of the modern "no more nails" types of adhesive or foam-in-a-can as used by window installers. Much quicker and no wood to rot.

Celotex/kingspan comes with its own vapour-barrier; fill the gaps between the edges of the Celotex with more expanding foam to stop 'indoor' damp getting in to the edges. Then panel over the lot with thin ply, and paint white to make it look nice.

You need to get some sort of 'fillet fillers' between the roof-corrugations and the walls to exclude the local rats/squirrels. Don't make things totally airtight though, or mould can become a hazard - your boat ventilators sound a good idea.

[Sinewave]

If you do use celotex, use aluminium foil tape to seal the joins between each celotex panel.

[avocollector]

Definitely get it up as far as you can off the ground. The difference I noticed between my sheds is with a foot or so of space underneath the moisture is significantly lower so tools don't rust etc. Get it up then place a layer of plastic sheet under the flooring - the walls can be treated as G6Tanuki suggests or 2x 2 battens bolted screwed to the frame, moisture barrier and glass fibre insulation followed by 7mm ply on the inside (heavier is even better for shelves etc.). What I'd like to do with mine (only 10sq m) one day is devise a low level heater - perhaps run off photocells on the roof and couple of car batteries that kicks in say below 8 Celsius to reduce condensation. Definitely insulate the roof - in the Summer you will be grateful for that. Cheers.

[Silicon]

You may find that rats will burrow under the slabs to nest there. They will eventually find the larger gaps between the slabs under the floor, and then use the underfloor area as a nest/toilet.

Have a look at Aquapanel, Hardiebacker and other cement based boards if you plant to have heat sources or consumer units in your shed. Plywood panels that have been cut to size could then have insulation panels glued on them before they are finally screwed into place. Thick plywood could support shelving.

[Stuart R]

Hello,

Thanks for your thoughts, there's a few ideas there. I don't think I'll be able to raise the floor any more than 4-6". I'm hoping they don't like the taste, so a squirt of expanding foam around the edges might keep the small creatures out of the base. I was thinking maybe I'll lift the original OSB floor and coat the underside with a bitumen paint or similar in an effort to make it less pleasant for nibbling rodents. Then re-lay it and cover with a membrane before laying beams, Celotex and a false floor on top. If I can fold the edges of the membrane upwards and stick to the sidewalls, surely that'll help stop the damp rising?

I can see that a timber frame around the walls might be un-necessary for most of the shed but it'll give a sturdy frame for future shelving - which is bound to be required in the future.

This could take a while.....

Regards,

SR

[David Simpson]

Stuart, have a look at Skyewave's thread in "Test Eq/Workshop" Section, started on 15th Aug. Concerning Thermal Insulation of his wooden shed.
There are some interesting posts & advice which would apply to a metal shed also. Certainly those relating to condensation, ventilation & heating. There are also present & past threads about "Earthing" - most important for vintage radio pursuits in a metal shed.

Regards, David

[ms660]

Don't export PME to a metal shed.

Lawrence.

[Stuart R]

Hello,

I've read a lot of the threads on workshop lining, but have completely missed that recent one from Skywave, so thanks for the reminder, David.

The Electrical Installation would be the topic for another thread, I've seen it can cause some lively discussions on Electrical forums and I realise this has a few challenges compared to more traditional outbuildings.

Regards,

SR

[broadgage]

As has already been said, rigid insulation board may be affixed directly to the inside of the metal walls, and this insulation board may be further lined with plywood.
If heavy shelves or equipment are to be fitted to the plywood this needs to be substantial and very well fixed.
I would bond the plywood to the insulation board with adhesive, but would not rely only on the adhesive. A length of substantial timber around the very top of the wall that is bolted through both the plywood and the insulation board to the structure will resist any tendency for the plywood to fall inwards.

It might be prudent to first paint the inside walls with a suitable rust inhibitor.

The void between the metal walls and the insulation should be sealed from the relatively warm and humid internal space, so as to reduce condensation in the void. Some condensation is still likely, hence my suggestion to apply rust inhibitor.

[Radio Wrangler]

How about spraying the inside of the steel with automotive anti-chip compound "Schutz"? it's waterproof and it makes a great sound deadener for when it's raining.

David

[Diabolical Artificer]

Swish shed, nice. Careful using expanding foam it traps water and rodents love to nest in it. prior to lining etc stopping any gaps with galvenised chicken wire helps keep out the critters, it can be balled up and poked in any holes.

Andy.

[Nymrod121]

Originally Posted by Diabolical Artificer

[chicken wire] can be balled up and poked in any holes.
Andy.

I used stainless steel scouring wool to discourage vermin from getting into our caravan via the various underfloor apertures. Being s/s, the wool is non-rusting and maintains gas drop functionality where needed.


My workshop's cable entry points are all at high level (power, GPS and VHF Band II antenna feeders). Following Lawrence's comprehensive advice/comments in another thread, the sub-floor area was treated with a commercial rodent deterrent and this is a regular maintenance item i.e. repeated at three month intervals by means of a pressurized sprayer fitted with an extension lance.

Best wishes
Guy