Recent Enquiries from Customers
Customer E-mail Enquiry: Roof renovation & Insulation
"We have a 1960s dormer-bungalow with concrete tiles on the roof. The roof is basically sound but the internal felt has got some holes in it. We have had a quote from Renotherm to spray the inside but as they were suggesting not stripping the felt, just spraying onto it, it seems a little insecure. We wondered about the possibility of filling the whole of the roof space with some sort of expanding product as if it didn’t produce too much pressure it would result in excellent insulation. Trawling through the net your cavity wall system struck me as a possibility. Is this a silly idea?"
Spray Insulation’s Response:
Renotherm were quite right about wanting to spray the foam onto the felt. This is a perfectly acceptable way of applying the insulation and would not be flimsy or unstable, as the foam sticks exceptionally well and forms a semi-rigid foam.
The foam will seal the holes in the felt by spraying the foam directly onto it. Another probable reason for not removing the felt, is that you probably have a ventilation gap between the felt and the tiles (this is one typical method of construction). Leaving the felt in place will keep the ventilation gap intact. Spray Foam is an excellent insulator; you would not need to fill your entire roof space.
The thickness of the foam required will depend on what insulation you already have in place in your home. Let us know how many m2 you have to spray and the depth you want to spray to and we will give you a quote for the DIY foam kits.
Customer E-mail Enquiry: Loft Conversion & U values
"I’m looking at options for insulating a roof as part of converting a loft. The area is at a guess around 150 square metres. Under the insulation will be plasterboard or wood depending on what we decide to clad it with. Would your spray foam be suitable and how thick do I need to spray to ensure against condensation?"
Spray Insulation’s Response:
The thickness of the foam will depend on the construction of your home and the extent of any insulation already in place. From your email, it appears you are converting a previously unused roof space to a living area. It is quite likely that you will already have some form of insulation in place at ceiling level (below the proposed loft floor). Assuming this insulation is mineral wool and around 4" thick, you will need to apply 75mm of spray foam insulation between the rafters to achieve a U value of 0.16W/m2.k. This will also prevent condensation.
An interesting point here, is that the U values are calculated in a holistic manner for the home, taking into account all layers in the building structure. If you have no insulation at ceiling level, then you would need approximately 130mm of spray foam insulation to achieve the same U value (0.16W/m2.k).
Please let us know if your construction differs from our assumption, as we will gladly calculate a foam thickness for the U value required by your local building control department.
Spray Insulation Ltd. has offices in the United Kingdom, and supplies The Republic of Ireland and Northern Ireland through our distribution center in Belfast.
tel. +44 (0) 1275 875 205 or email us and we will gladly call you back
