Insulation in attic storage area

Confusedcom

I have an attic conversion which has some draft issues. One of them is caused by cold air leaking into the room from the storage areas through badly fitted doors which I am going to rectify, another is unsealed downlight fittings which I am going to change to sealed units. The rafters are insulated with kingspan (with 50mm air gap) but this only goes down to the half walls and not into the eaves area. The back of the storage area walls are insulated with Kingspan as well.

What I am wondering is can I use rockwool flexi slabs inside the storage areas in between the rafters, leaving the air gap, and rockwool along the eaves whilst still leaving the air vents free to let air circulate?

MicktheMan

Confusedcom wrote: »

What I am wondering is can I use rockwool flexi slabs inside the storage areas in between the rafters, leaving the air gap, and rockwool along the eaves whilst still leaving the air vents free to let air circulate?

You can but I doubt it will be of any benefit if I am understanding you correctly.

Confusedcom

MicktheMan wrote: »

You can but I doubt it will be of any benefit if I am understanding you correctly.

I'm thinking it would stop a lot of the cold air and drafts especially when it's windy out? It's like a pressure cooker in the storage areas when it's windy and the hatch doors open themselves sometimes.

dodzy

Confusedcom wrote: »

I'm thinking it would stop a lot of the cold air and drafts especially when it's windy out? It's like a pressure cooker in the storage areas when it's windy and the hatch doors open themselves sometimes.

Your plan of attack in the OP Is solid. It will definitely help. I’m assuming the access doors are insulated? You need to address the latching mechanism on these as you know, and ensure seal strips are well fitted and functional. Unfortunately It looks like the converter cut a few corners to save a buk.

Confusedcom

dodzy wrote: »

Your plan of attack in the OP Is solid. It will definitely help. I’m assuming the access doors are insulated? You need to address the latching mechanism on these as you know, and ensure seal strips are well fitted and functional. Unfortunately It looks like the converter cut a few corners to save a buk.

Thanks Dodzy, the access doors have Kingspan on the back of them and you're right there is no point doing any of this unless the doors are airtight which I will make sure they are this time!
Any idea if it would be worth while putting foil bubble insulation over the rockwool slabs or would that just be overkill? I am conscious that there still needs to be airflow in that area to allow the entire roof to breath and stop condensation, do you think that leaving just the soffit vents completely free would be enough to achieve this? Last thing I want to do is cause further problems.

MicktheMan

Confusedcom wrote: »

I'm thinking it would stop a lot of the cold air and drafts especially when it's windy out? It's like a pressure cooker in the storage areas when it's windy and the hatch doors open themselves sometimes.

You thinking is wrong.:)

If the access doors are blowing open when windy and all windows and external doors are closed, you have significant air leakage issues elsewhere within the thermal envelope of the house, not the crawl space. Remember, air will only enter a house if it is exiting somewhere else.

This air leakage first needs to be identified and then dealt with.

By all means ensure the access doors are properly air sealed when closed. Treat the crawl space on the other side of these doors as outside.

mickdw

If i underatand right, you are attempting to go from a situation where the side attic are external to a situation where the side attics are insulated - keeping the roof ventilation outside that envelope.
If done well, it could be a plan but difficult to do well inna finished dormer house.

Confusedcom

MicktheMan wrote: »

You thinking is wrong.:)

If the access doors are blowing open when windy and all windows and external doors are closed, you have significant air leakage issues elsewhere within the thermal envelope of the house, not the crawl space. Remember, air will only enter a house if it is exiting somewhere else.

This air leakage first needs to be identified and then dealt with.

By all means ensure the access doors are properly air sealed when closed. Treat the crawl space on the other side of these doors as outside.

Thanks for that MicktheMan, is it possible that the air is entering one side of the room and exiting the other side as the crawl space doors are bad on both sides, or through the 5 downlights in the ceiling in the attic? I have noticed that when it is particularly windy out the door into the attic almost resists closing as if air is rushing up the attic stairs from downstairs, does that make sense?

MicktheMan

Confusedcom wrote: »

Thanks for that MicktheMan, is it possible that the air is entering one side of the room and exiting the other side as the crawl space doors are bad on both sides, or through the 5 downlights in the ceiling in the attic? I have noticed that when it is particularly windy out the door into the attic almost resists closing as if air is rushing up the attic stairs from downstairs, does that make sense?

Where do you think the air that is "rushing up the attic stairs" is coming from if all doors / windows are closed?

This is what I meant by saying previously that there are probably major leakages elsewhere within the thermal envelope.

Adding insulation to the rafters will not address this issue. In fact, this is not an insulation issue but rather an air tightness one. Maybe, do some research on air tightness first.

Confusedcom

MicktheMan wrote: »

Where do you think the air that is "rushing up the attic stairs" is coming from if all doors / windows are closed?

This is what I meant by saying previously that there are probably major leakages elsewhere within the thermal envelope.

Adding insulation to the rafters will not address this issue. In fact, this is not an insulation issue but rather an air tightness one. Maybe, do some research on air tightness first.

Yeh that makes sense alright, thanks for that I think you might be 100% right, I've a slight idea about air tightness, I think there might some issues around positive or negative air pressure in the house to be honest, not sure which is which, I assume blocked vents would lead to negative pressure. There is some vents blocked up and a chimney balloon which could be adding to the issue? For example I can feel a pretty bad draft through the front door keyhole (new composite door) and from the downstairs toilet push plate, light switches etc which feels like they are sucking air into the house. Do you think this could be causing the airflow up to the attic? Any home made solutions to finding air leaks etc that you may know of I'd appreciate, thanks. (wet hand is the only way I know

lucalux

Confusedcom wrote: »

Any home made solutions to finding air leaks etc that you may know of I'd appreciate, thanks. (wet hand is the only way I know

I've used candles before?
Tea-lights lit and put on floor to find draughts coming in from under floorboards, or using a tall candle in a holder, move candle around windows to find poor seals etc .

MicktheMan

It's all cumulative. So a hundred small leaks will result in a large flow of air.

You won't notice warm air leaving the house as much as cooler air entering with your damp hands (backs of fingers tend to be more sensitive to air movement).
lit incense sticks can be useful.
Check out all junctions (e.g. floor to wall / wall to window frame) and cable / pipe penetrations of floors / walls / ceilings ... incl internal elements.