Some buildings are not a straight forward installation
Take this one, it has a lower section with cavity walls, an upper section of internal wall and external tin with a metal roof. The building will be converted to homes. It also already has wool sporadically placed between the wall and the tin walls. It will have a mezzanine floor built inside.
There are a variety of ways to deal with a building like this.
The Roof
We can insulate the roof with Lapolla Closed Cell Spray Foam. This expanding foam would create the best insulation and thermal barrier to maintain warmth and achieve your EPC rating and will bond well to the tin roof. Because of its properties you will be able to maximise space and celling height as the cavity between insulation and new ceiling will not have to be as deep as other methods. It will also soften the sound of the rain on a tin roof.
We would spray this directly onto the metal work before you attach any ceiling to the roof structure, but preferably after you have added any windows into the roof and added the extra first floor area.
First floor
The under section of the first floor would benefit from our open cell foam. This is because the foam will act as a sound retardant along with added thermal barrier protection.
The best time to spray this would be when both floor sections are in position, the electrics and plumbing have been run and before a ceiling has been fitted.
Insulation Extraction
The current insulation may be behind all the tin areas and not in lower section of wall in-between the two bricked wall cavities, so we could extract this.
An alternative would be to remove the tin panels and pull out by hand, assuming there is no more insulation in the lower sections.
Wall Cavity Insulation
We generally use a product called Thermabead for cavity wall insulation. This is the leading bead product available in the UK and its more cost efficient than using spray foam in the cavity. It uses EPS beads with groves to ensure that any moisture falls down them and not across to keep the inner cavity wall dry. It is also injected with a glue to hold in position. This comes with an insurance backed guarantee. But we ensure we do the job right to avoid having to ever return.
However, it can not be used in the upper section against the tin. If anyone you speak to offers you anything other than closed cell spray foam for this application, be very cautious. The tins temperature will cause moisture in the void if insulated with foam beads.
With this in mind we can approach the walls with the following different options.
A: Blow in Lapolla Closed Cell Foam for the upper wall section and Thermabead for the lower half.
B: Leave the current insulation in place and fill the lower half only with Thermabead.
C: Blow in the spray foam top and bottom.
D: Thermabead in the lower section and leave the current insulation in place
As you can see this is not a straight forward job with having a tin wall.
