Barn restoration to storage garage conversion part 7, new tin sheets fitted and spray foam

In part 7 of this barn conversion / restoration into a storage garage for the various projects we finally get the new galvanised corrugated tin sheets fitted and add some spray foam to the underside to reduce the chance of condensation
please remember to like and subscribe and hopefully the next one will follow shortly
thanks
Paul

[@dewiroberts8591]

Glad you've got the barn done Paul,onwards to the workshop now.

[@paulsprojects1]

yeah im glad its nearly done too, got so much to catch up on lol

[@clivewilliams3661]

The foam will be an expensive waste of time and money. Whilst the corrugated iron will create condensation, the amount of foam will not raise the surface temperature above the dew point and thus condensation will still form although maybe not as visible due to the texture of the foam. One issue will be that the corrugated sheeting has not been foamed over the top of the purlins but the foam has partially cut off the passage of air over the top of the purlin so that any condensation is trapped and will drip on top of the timber that over time will rot, that air flow was vital to keep the timber dry. By far the best way to prevent condensation is to treat the roof as an industrial one with another skin of sheeting over the first and insulation between. This is why the standard liner panel on such a roof is only 0.9mm thick. Standard industrial roofing materials can be bought cheaply since there are many times when roof sheets are cut from the roll in error thus making them surplus.

[@paulsprojects1]

I appreciate the comment, would love to have fitted insulated panels but they're certainly not cheap and the box profile wouldn't have been in keeping with the rest of the corrugated barn would I be better off filling the gap above the purlins with foam?

[@clivewilliams3661]

@@paulsprojects1 You don't understand what a standard industrial roof is. It is formed using a thin liner sheet with a 19mm profile fixed to the purlins, there are then galvanised horizontal spacer Z bars fixed through the liner sheet into purlins, fibreglass insulation is laid over the liner sheet between the Z bars. and then the top finish sheet is fixed to the Z bars. That top sheet can be standard corrugated tin if you want to match your main roof. The height of the Z bars can be set to suit the depth of the insulation from 50 - 250mm. You don't have to comply with the insulation requirements of the Building Regs, being an agricultural barn so that the insulation can be set to suit that required for condensation control. This form of construction has been the most common used in industrial buildings for at least 50 years. What you are thinking of is the complete foam insulated bonded panel that is a totally different and more expensive animal. Apart from the condensation control aspect, another issue will be noise. In pouring rain the noise on the flat corrugated roof will be excessive and at times deafening. It isn't an issue with a barrel vault because that rain mostly strikes any part of the roof obliquely. Filling the gap over the top pf the purlins is problematic as the spray foam needs to be at least closed cell foam. The common open cell foam is vapour permeable and will allow the passage of vapour and condensation. Also the corrugated iron is in direct contact with the purlin and therefore has no insulation at that point and the foam will just hold the water produced.

[@paulsprojects1]

@@clivewilliams3661 cheers for that, yeah I'm no builder/ roofer that's for sure, noise isn't really an issue as its for storage only tbh but thanks for the info