Draught under first floor

[Molebob]

I have noticed that there is a rather cold draught coming through the upstairs floorboards in the bay window on the main bedroom. As the bay sits upon a small roof (is there a name for this arrangement?) it appears the air is coming in through the roof. Looking under the floorboards shows that there is an intentional gap (the second pic is the wood under the bay).

I was thinking of putting some insulation down there but I wonder what type? I am concerned that if I am not careful I will get condensation forming and cause myself more issues than I solve.

Untitled

• Molebob
• 25 Mar 2013
• 1

Untitled

• Molebob
• 25 Mar 2013
• 1

Untitled

• Molebob
• 25 Mar 2013
• 1

 

[pinenot]

It looks like your getting external venting trough this section of roof into the room, so I would pack the void with glass fiber wool in the first instance this should provide insulation and still allow an airflow through it. You could leave the floorboards somewhat accessible so that you could check for moisture within the insulation now and again. If you don't find any, fix permanently, it's the only way to make sure...pinenot

 

[Molebob]

It looks like your getting external venting trough this section of roof into the room, so I would pack the void with glass fiber wool in the first instance this should provide insulation and still allow an airflow through it. You could leave the floorboards somewhat accessible so that you could check for moisture within the insulation now and again. If you don't find any, fix permanently, it's the only way to make sure...pinenot

That is roughly what I planned for the short term. It really is a large amount of air coming in. Obviously the carpet when installed will help too. I wonder if there is a better long term fix involving redoing the roof?

 

[^woody^]

It's not intentional, upper floors do not need ventilating and should not be.

Expanding foam or dense quilt will block it

 

[Molebob]

It's not intentional, upper floors do not need ventilating and should not be.

Expanding foam or dense quilt will block it

I will assume poorly built rather than intentional.

My concern was condensation forming and the wood becoming wet if I blocked it. I will use a quilt and check upon the area here and there to keep an eye on it.

 

[^woody^]

That location is not a condensation risk