Increased Ventilation and Loft Insulation Thickness Advice

[headfi]

Hi all,

This is my first post and could do with some advice. I am in a top floor flat with a peaked roof with 2 bedrooms on one side and kitchen lounge on the other, hall/bathroom up the middle.

I have just recently had some broken tiles replaced above the bedrooms which was causing damp and mould to grow on the underside of the wood/felt on the roof slope.

The tiles were replaced but the the damp remained during the cold weather. The roof was deemed water tight on the outside so 6 cowl/low profile cube type vents were put on, 3 each side each slope and some vents at the peak as well to remove what they thought was condensation. This was done by the factors of the building.

Now I have 6 square holes through the wood/felt, 3 each side and wondered if it worth putting grilles over the hole to prevent any insects etc getting in and to tidy it up? Do these vents have grilles on the outside?

Also, one half of the loft has 250mm insulation (over the bedrooms), boards down the middle with 150mm underneath and 150mm of insulation over the other side (kitchen and lounge). Is it worth topping up the insulation over the kitchen and lounge now I have more air flow in the loft? I find these rooms a lot warmer than the two bedrooms on the west side even though there is less insulation. Is there any point in adding another 100mm if the rooms are already warm?

I look forward to some replies! Thanks

 

[Alastairreid]

Now I have 6 square holes through the wood/felt, 3 each side and wondered if it worth putting grilles over the hole to prevent any insects etc getting in and to tidy it up? Do these vents have grilles on the outside?

the vents have insect screens incorporated in their design.

loft insulation should be a minimum of 250mm the more the better.

 

[headfi]

Thanks for the response, I'll just leave the vent holes alone and ensure they are properly weather/insect proof.

With regard to the insulation. I added another 100mm (total now 250mm)above the west facing bedrooms because they were the coldest part of the flat. I didn't notice any difference in heat retention in those rooms and most is probably going out the outside walls and windows.

There must become a point where adding insulation makes no difference, Is there a big difference in heat retention between having 150mm and 250mm? I think it's all a bit exagerated. Does anyone know?

 

[Alastairreid]

take a look.

www.energysavingtrust.org.uk/Home-improvements/Home-insulation-glazing/Loft-insulation -

 

[stuart45]

Over 300mm is not considered cost effective.

 

[headfi]

Thanks for that. I'll add another 100mm above those rooms when I get time.

It's strange though that there is less insulation yet these rooms are a lot warmer. They have the same outside walls etc. Must be purely down to being on the sheltered side of the building.