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Workshop Insulation
To minimise damp and condensation in my new wooden garage, I am considering boarding it out and using foil backed bubble wrap between the wall and board. I shall do the same on the roof with some sort of rubber floor covering. Has anyone else done this and, if so, was it effective? There will still be air flow under the doors. I know that it will not be as effective as Kingspan or Rockwall.

I have done mine with Kingspan (expensive but effective ) and painted the floor with Screw fix floor paint.
hi jamie,

ive done simular in my barns, i couldnt accept the prices of doing it properly.

i used polistyrene sheets in the walls, it keeps the drafts from between boards etc.

and gym matting from ebay for the floor.

i just ordered some more for the barn recon thread im doing.

but do remember any shed that is not heated, the temp will gradually drop with the outside temp. as you say you will still have the air flow under the door.

were insulation works well, is with just a very small heater. you will feel a large difference inside the garage.

The advantage with Kingspan is ease of fitting and the reflective layer. Pricey but good. Condensation is always a major problem so do make sure you get a free movement of air where possible and necessary.
Hi Jamie

We recently had a small leak in our house roof.  The builder commented that our plastic felt wasn’t used any more due to condensation problems.  

I think wherever you put an impermeable barrier there is the possibility of condensation. On a summerhouse I built some years ago I used “building paper” behind the joists, simple glass fibre loft insulation between and match board internal lining. Had no condensation problems.

It’s all down to dew points which is perhaps a bit complex for a simple shed. I’d avoid bubble wrap if I were you as it doesn’t provide a huge amount of insulation and provides an impermeable surface against which condensation can form.


Hi Jamie

I recently used EcoQuilt Expert it is meant to be better than foil bubble wrap.  It uses three layers of foil and a quilt inside, it is meant to be the equivalent of 100mm insulation but 15mm thick.

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My shed / garage is a bit of an odd ball in that two walls are corrugated iron and two timber with timber double doors, the floor is paving slabs on sand on a dpm, the sand got at bit wet so may still be drying out.  But insulated using the above as getting condensation the insulation helped a bit in particularly on the corrugated iron but not fixed the problem.  So now putting 100mm holes with grills to give a good air flow, hopefully this will fix the condensation.  But as the condensation is weather dependant it is difficult to see if it is improving or just the weather is changing.  Still the car is not in it yet.

The condensation will form between two surface of a different temperature.  So heat and or vent should fix it.  Although I have see condensation on the underside of a plastic car port!
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I've built high-end timber garages for a living for 35 years. They're great for classic and vintage cars, as properly constructed they should be very dry.

The critical thing is to allow the timber to breath. Don't line the building with anything impermeable.

My own preference is 50mm fibreglass insulation, with a 9/10mm ply lining - neither very expensive in the great scheme of things.
Thank you for all of the suggestions and advice. I shall have a proper think and look at the different suggestions before starting. I need to let the place dry a bit first, though. It had obviously been on the lorry over night and been rained on. The floor is quite damp, although the walls and ceiling seemed to have dried pretty much.


I've used foil backed bubble wrap in my garage for the roof and it's brilliant,  what do people use for heaters in the winter ?
Be careful if using polystyrene insulation near electrical cabling, it causes the PVC insulation to migrate over time, I have seen it where there are only bare conductors left after a number of years. (Also mice seem to like it!)
I used a mixture of leftover Kingspan type insulation from our kitchen extension and fibreglass insulation.

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