Fiberboard is not an insulation.
Cold flat roof insulation thickness.
Cold deck flat roof the thickness of insulation required will vary depending on the material you decide to use and the manufacturer s specification.
If you are upgrading the roof to meet current thermal requirements then the thickness of insulation will vary depending on its thermal conductivity.
Refurbishing an existing timber joisted flat roof which has no insulation.
Between and under joists.
The typical u value of an existing uninsulated flat roof is 1 5w m2k.
The target should be to achieve a u value of 0 25w m2k or better.
Kingspan and recticel are the two of the most well known flat roof insulation brands and they re firm favourites of insulation superstore customers.
A cold flat roof is one where the insulation is between or between and below the roof joists.
While insulation for a flat roof is expensive and can account for as much as 25 of the total installation.
With a flat roof this issue does not arise but the u value constraint and the amount of insulation needed is just the same.
To achieve this add 100 to 160mm of insulation above the structural deck dependant upon insulant conductivity.
Unless the joists are exceptionally deep there is also likely to be a requirement to install insulation to the underside of the joists as the upper 50mm of joist space is usually required to be left clear for ventilation purposes.
A ventilation gap usually 50mm should be.
120mm of kingspan tr26 or similar will make the.
It has only 1 r value per inch and is always installed in 0 5 inch thickness.
It allows insulation to be added without having to replace the waterproofing on.
Therefore you get practically 0 r value out of it.
Additionally attic condensation and leaks will make fiberboard wet.
This is used for refurbishment e g.
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.
It should be of the maximum available thickness.
Cold deck the thickness of insulation required will vary depending on the material you decide to use and the manufacturer s specification.
The insulation is below the deck but above the plasterboard.
