The Importance of Airtightness in a Building Envelope
What do we mean by airtightness?
Many people get confused and think that if somethings airtight it’s going to trap moisture and cause materials to sweat, especially where spray foam insulation is concerned.
Put simply, something that’s airtight has the ability to stop mass transfer of air. Which does not always mean stopping the ability to pass moisture vapour (breathe) if the product is breathable.
Air movement around poorly fitted insulation boards via convection will lose far more heat at a much faster rate than through heat loss via conduction of an airtight material.
If you were to leave your fridge door open just a small amount it would soon stop cooling things down. As little as a 5% gap around an insulation board can equate to a 50% loss in thermal efficiency.
Air leakage control is essential for improving
- Indoor air quality
- Limiting heat losses due to convection and mass transfer
- Avoiding mould growth
- Limiting airborne noise from the outside
- Improving effective U value
U Value
The U value of a building can be greatly reduced if the insulation product is not fitted correctly. We have seen countless times where an insulated boards are fitted in a vaulted ceiling and a hole is cut in the middle of the board for lighting. That hole goes directly through to a cold ventilated space above and will greatly reduce the U value of that section. This is due to the heat lost via convection through the hole. It will also allow cold air to push into the building from the outside.
Open cell spray foam insulation is an insulator and air barrier material all in one. It expands 100x to fill every gap and stops heat loss through air leakage, convection, and mass transfer. It’s a fully breathable product that will allow moisture vapour diffusion allowing materials in contact to continue to breathe.
Airtightness is key to a building’s energy efficiency; you can have all the insulation in the world but if you leave the front door open its always going to be cold. Control air leakage and you will be well on your way to achieving an energy efficient home.
Spray foam insulation is a key component in achieving an airtight building envelope.
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Government funding and grants, currently available for spray foam insulation
Of late we’ve been inundated with customers asking about government schemes, informing us of offers from companies offering grants of £1500 for spray foam insulation. We like to think we know our stuff when it comes to all things spray foam and we wanted to share our knowledge with you. Hopefully this article should shed some light on what is and isn’t available grant wise and help you avoid any potential hard sell tactics.
We appreciate that information can sometimes change quickly, therefore we always advise you to do your own research when looking at what funding is available. There are numerous reputable sources where you can check for the most recent funding options, The government website (www.gov.uk/topic/housing/funding-programmes) is always a good one to check, likewise the money saving expert website (www.moneysavingexpert.com) can be a great source of up to date information.
The most recent grant scheme available was the ‘Green Homes Grant Scheme’ this was a government funded scheme to help homeowners pay for the cost of energy efficiency measures to their homes by contributing 2/3rds of the cost to qualifying customers. When the scheme was launched in September 2020, the Government pledged £3billion to making UK homes greener, on the face of things the scheme looked great, but things unfortunately turned sour. Customers were struggling to find installers and there was a minefield of paperwork and regulations for installing companies making it almost impossible to get it set up effectively. The scheme was eventually cut short by the government and scrapped for new applicants in March 2021.
Although there may be some funding options for other measures within your home, spray foam insulation is not currently on that list. Currently there are several companies advertising grants of £1500 for spray foam insulation, saying all you need to do is fill in one form with your contact details and they will let you know if you’re eligible. At the time of writing this there currently are not any grants available for spray foam insulation for pitched roofs or underfloor. If you hear of any grants available, we advise you to do your own research. Find out where this funding is coming from and check its not just a sales ploy, and that you are not actually paying an inflated price for the services you require under the premiss you are qualifying for a grant.
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