New Extension Roof Insulation

If you are constructing a ventilated roof insulating between and under the rafters then there needs to be a 50 mm air gap between the insulation and the sarking felt to avoid condensation building up.

New extension roof insulation.

K for properties in england and wales and 0 10 w m 2. Whether you re doing a weekend fix or folding it into a bigger home renovation insulating your roof will pay off for years to come. I will be building an extension to the rear of my property shortly and will be having a lean to roof with pitched roof inside with two sky lights. Hi i have a flat roof extension built in the 1970s.

New roof extension same construction. The extension will be 3 5x6x3 5m. Choose feldco roofing for your brand new roof. Due to a rewire i ve had to remove parts of the plasterboard ceiling and have found that there is no insulation in the roof i can see the roof deck and joists there is no vapour layer and the plasterboard is not foil backed.

In a warm pitched roof it is important to ventilate above the insulation line to avoid condensation so ensure that fascia vents give access for cold air to circulate. Celotex a 225mm solid brick wall will have a u value of around 1 7w m k and a 400mm stone wall about 1 4. I need to reach 0 18 u value and minimise the depth of insulation as i will be left with a step between original and new slopes. Cold deck the thickness of insulation required will vary depending on the material you decide to use and the manufacturer s specification.

The roof covering is then laid over the ply. How does this ceiling have to be insulated and what sort of materials will i need. Column b is for other extensions upgraded existing thermal elements non exempt conservatories and conversion of unheated buildings. Whole roof will have a new breathable membrane.

Column a is for extensions where the existing dwelling s walls and roof u values are worse than 0 70 w m k in the walls and worse than 0 25 w m k in the ceiling. 70 s chalet with 100 50 rafters at 410 centres. A ventilation gap usually 50mm should be provided between the top of the insulation and underside of the roof covering to allow the air to flow across. Adding 50mm of rigid insulation will reduce the u value to around 0 4 while 50mm of mineral wool or natural insulation will reduce it to 0 5.

Insulation puts the money back in your pocket by protecting your home from the elements and lowering energy costs. K for scottish homes. Kingspan with a flat roof this issue does not arise but the u value constraint and the amount of insulation needed is just the same. For a new build property we recommend a target u value of 0 11 w m 2.