cost effective insulation for metal shed.

andy_drummer

I have a large metal shed, which drips with condensation off the roof. I have fitted guttering inside below the joists which has worked quite well, (directing the water into buckets, and keeping it off the bench) and also used a demidifier.
I want to empty out the shed when the weather is fit, build a better bench and do a decent job of insulating.
has anyone had any success of this.
any info appreciated.

pelo_2

Make sure there's a gap around the top between wall and lid, air movement will help no end.
Polystyrene boards screwed up will help as well

snowcat75

I work in a steel workshop, you can get pre insulated box profile, or fix insulated board on the existing, you can buy 30mm seconds from about £9, new it will cost double.


The condensation problem will remain however unless you willing to heat the shed and keep it above the due point, I have a lot of machinery in mine and although dry and boarded unless I keep all the machines warm they will condensate a run with water.

Nilrem

We are currently looking at something called Graphotherm for our garage (which has a metal roof), to help with the condensation, apparently you get it in a tub, and use a paint sprayer with a compressor to apply it.
It basically has the effect of adding an insulating layer direct to the underside of the metal, and apparently has been used in places like warehouses and shipyards/submarine pens to reduce/stop the condensation on existing structures where replacing the roof/other insulation would be either too expensive, or time consuming/disruptive to put into place.

IIRC for our (double+) garage the quote was about £300 or £400 for it, if we applied it ourselves.

The airflow helps if it's possible, but with a metal roof unless you either keep it warm (expensive), or have something directly in contact with the metal surface you'll pretty much always get some condensation.

snowcat75

Heating can be reasonably cheep if you put the money into insulation and the right kind of heating, My shed outside is about 72cu/m and heated with indirect kero/diesel to 12 degrees it costs about £5 week.


My workshop however which has to be vented with extractors for welding and is around 600cu/m costs a good £20 a day (8hrs), and on cold days the welding booth will struggle to get much above a few degrees, as essentially your sucking the heat straight out into fresh air.

Furts

My sugestion would be... First it needs moisture resistant insulation, hence fibreglass and Rockwool are useless. For this Celotex, Kingspan, etc would be better than polystyrene for they are more robust and better insulating. Yes they cost more, so OP may not be happy with this. Then moisture must be prevented from rising into the insulation - hence a polythene membrane beneath it. Then the moisture in the insulation must breath - hence a breather membrane like Tyvek above it. This moisture must vent away - hence an air gap with adequate ventilation to purge it. The sheets will still be prone to condensation, but the Tyvek, or similar, is a one way breather so this moisture, or dripping, will not penetrate it.