Question 1

Is spray foam insulation in the roof a problem?

Accepted Answer

It can be a serious one. Foam applied to the underside of a roof can trap moisture against the timbers, it makes the roof structure impossible to inspect, and it can make a future re-roof considerably more expensive. A number of lenders and surveyors take a firm line on it at mortgage and valuation stage. Spray foam applied to the underside of a pitched roof has been widely sold as an insulation upgrade, and it causes more problems than almost anything else in this trade. The technical objection is moisture. A cold roof needs to be ventilated so that moisture rising from the house can escape. Foam sprayed onto the underside of the covering — particularly closed-cell foam directly against the underlay and the rafters — can block that path and hold moisture against the timber, which is precisely the condition that rots roof structure. Some installations are designed to manage this; a great many are not. The inspection objection is at least as serious. Once the underside of the roof is covered in foam, nobody can see the battens, the underlay or the rafters. A surveyor cannot assess the roof structure, which means they cannot confirm it is sound — and a surveyor who cannot confirm something reports it as a risk. That is the mechanism by which spray foam becomes a lending problem rather than merely a technical one. The removal objection is money. Foam bonded to the underside of the slates or tiles and to the battens can make a future strip considerably more expensive, because the covering cannot simply be lifted off and salvaged. On a slate roof where the slates would otherwise have been re-laid, that can turn a re-roof into a materially bigger bill. The lending position is the practical one for most people. Reports of lenders declining mortgages or requiring removal on properties with spray foam have been widespread enough that it is a real consideration if you might sell or remortgage within the next decade. It is worth checking the position with a broker before having it installed rather than after. If you already have it, do not panic — but do get it looked at by somebody independent of whoever installed it, and keep any documentation about the type of foam and how it was specified. Where it has been correctly designed with a ventilation strategy, the position is much better than where it was simply sprayed on.

Question 2

Spray foam and mortgages

Accepted Answer

It can be a serious one. Foam applied to the underside of a roof can trap moisture against the timbers, it makes the roof structure impossible to inspect, and it can make a future re-roof considerably more expensive. A number of lenders and surveyors take a firm line on it at mortgage and valuation stage. Spray foam applied to the underside of a pitched roof has been widely sold as an insulation upgrade, and it causes more problems than almost anything else in this trade. The technical objection is moisture. A cold roof needs to be ventilated so that moisture rising from the house can escape. Foam sprayed onto the underside of the covering — particularly closed-cell foam directly against the underlay and the rafters — can block that path and hold moisture against the timber, which is precisely the condition that rots roof structure. Some installations are designed to manage this; a great many are not. The inspection objection is at least as serious. Once the underside of the roof is covered in foam, nobody can see the battens, the underlay or the rafters. A surveyor cannot assess the roof structure, which means they cannot confirm it is sound — and a surveyor who cannot confirm something reports it as a risk. That is the mechanism by which spray foam becomes a lending problem rather than merely a technical one. The removal objection is money. Foam bonded to the underside of the slates or tiles and to the battens can make a future strip considerably more expensive, because the covering cannot simply be lifted off and salvaged. On a slate roof where the slates would otherwise have been re-laid, that can turn a re-roof into a materially bigger bill. The lending position is the practical one for most people. Reports of lenders declining mortgages or requiring removal on properties with spray foam have been widespread enough that it is a real consideration if you might sell or remortgage within the next decade. It is worth checking the position with a broker before having it installed rather than after. If you already have it, do not panic — but do get it looked at by somebody independent of whoever installed it, and keep any documentation about the type of foam and how it was specified. Where it has been correctly designed with a ventilation strategy, the position is much better than where it was simply sprayed on.

Question 3

Should I remove spray foam from my loft?

Accepted Answer

It can be a serious one. Foam applied to the underside of a roof can trap moisture against the timbers, it makes the roof structure impossible to inspect, and it can make a future re-roof considerably more expensive. A number of lenders and surveyors take a firm line on it at mortgage and valuation stage. Spray foam applied to the underside of a pitched roof has been widely sold as an insulation upgrade, and it causes more problems than almost anything else in this trade. The technical objection is moisture. A cold roof needs to be ventilated so that moisture rising from the house can escape. Foam sprayed onto the underside of the covering — particularly closed-cell foam directly against the underlay and the rafters — can block that path and hold moisture against the timber, which is precisely the condition that rots roof structure. Some installations are designed to manage this; a great many are not. The inspection objection is at least as serious. Once the underside of the roof is covered in foam, nobody can see the battens, the underlay or the rafters. A surveyor cannot assess the roof structure, which means they cannot confirm it is sound — and a surveyor who cannot confirm something reports it as a risk. That is the mechanism by which spray foam becomes a lending problem rather than merely a technical one. The removal objection is money. Foam bonded to the underside of the slates or tiles and to the battens can make a future strip considerably more expensive, because the covering cannot simply be lifted off and salvaged. On a slate roof where the slates would otherwise have been re-laid, that can turn a re-roof into a materially bigger bill. The lending position is the practical one for most people. Reports of lenders declining mortgages or requiring removal on properties with spray foam have been widespread enough that it is a real consideration if you might sell or remortgage within the next decade. It is worth checking the position with a broker before having it installed rather than after. If you already have it, do not panic — but do get it looked at by somebody independent of whoever installed it, and keep any documentation about the type of foam and how it was specified. Where it has been correctly designed with a ventilation strategy, the position is much better than where it was simply sprayed on.

Question 4

Is spray foam bad for a roof?

Accepted Answer

It can be a serious one. Foam applied to the underside of a roof can trap moisture against the timbers, it makes the roof structure impossible to inspect, and it can make a future re-roof considerably more expensive. A number of lenders and surveyors take a firm line on it at mortgage and valuation stage. Spray foam applied to the underside of a pitched roof has been widely sold as an insulation upgrade, and it causes more problems than almost anything else in this trade. The technical objection is moisture. A cold roof needs to be ventilated so that moisture rising from the house can escape. Foam sprayed onto the underside of the covering — particularly closed-cell foam directly against the underlay and the rafters — can block that path and hold moisture against the timber, which is precisely the condition that rots roof structure. Some installations are designed to manage this; a great many are not. The inspection objection is at least as serious. Once the underside of the roof is covered in foam, nobody can see the battens, the underlay or the rafters. A surveyor cannot assess the roof structure, which means they cannot confirm it is sound — and a surveyor who cannot confirm something reports it as a risk. That is the mechanism by which spray foam becomes a lending problem rather than merely a technical one. The removal objection is money. Foam bonded to the underside of the slates or tiles and to the battens can make a future strip considerably more expensive, because the covering cannot simply be lifted off and salvaged. On a slate roof where the slates would otherwise have been re-laid, that can turn a re-roof into a materially bigger bill. The lending position is the practical one for most people. Reports of lenders declining mortgages or requiring removal on properties with spray foam have been widespread enough that it is a real consideration if you might sell or remortgage within the next decade. It is worth checking the position with a broker before having it installed rather than after. If you already have it, do not panic — but do get it looked at by somebody independent of whoever installed it, and keep any documentation about the type of foam and how it was specified. Where it has been correctly designed with a ventilation strategy, the position is much better than where it was simply sprayed on.

Is spray foam insulation in the roof a problem?

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