Decking, Air bricks and Ventilation.

[moustachebandit]

Wonder if anyone can help with some advice? I might just be over thinking this.

My house has a sloping plot and to level off some of the garden to make a usable seating / patio area I was going to install some decking which will sit tight to the side of the house (plan is to take out the kitchen wall and install bifolds so it opens out into the garden) and extend out over part of the garden.

My main concern is that the decking will have to sit above 2 air bricks on the side of the house. Can anyone tell m if this would this cause an issue with restricting ventilation under the house? I don't want to cause dry rot.

This is the sort of thing we are going for

http://www.wrtimbers.com.au/wp-content/uploads/201...

My concern is that the decking wont allow much ventilation to pass through and whilst there are numerous other air bricks around the property I don't want to create an issue by limiting the air flow under the property.

All opinions are appreciated.

Ta,

James

[Tom_C76]

As long as you don't directly block the airbrick or infill under the decking it'll work just fine

[drmotorsport]

I have exactly the same issue and spent ages agonizing over ways to get a paved patio to work nicely with air bricks, before settling on composite decking boards. I'm going for the traditional 5mm gap between boards which will allow plenty of airflow to the bricks which will end up just below the board level.

Looks from your photo however that yours might a tongue/groove style which might not be so ideal?

[moustachebandit]

Thanks for the responses - the look we are after means that the deck boards are going to be really tight together and as we are trying to hide away all the crap terracing / concrete paths underneath the decking it will be totally enclosed so air moment will be pretty limited.

I am thinking that for piece of mind installing some of these remote void vents means that I can ensure that the air bricks get some positive ventilation at least rather than hoping there is enough air moment under the decking to help with ventilation.

http://www.manthorpe.co.uk/Building/Products/Throu...

[herewego]

The main issue is to be sure the decking is 150mm below DPC.

[moustachebandit]

Unfortunately the decking will sit above the DPM due to the levels and the way the house is constructed. All I can do is leave a decent gap between the house and the decking so water isnt able to collect against the brickwork above the DPM.

[roofer]

moustachebandit said:

Unfortunately the decking will sit above the DPM due to the levels and the way the house is constructed. All I can do is leave a decent gap between the house and the decking so water isnt able to collect against the brickwork above the DPM.

Correct.

[herewego]

moustachebandit said:

Unfortunately the decking will sit above the DPM due to the levels and the way the house is constructed. All I can do is leave a decent gap between the house and the decking so water isnt able to collect against the brickwork above the DPM.

As I understand it the issue is rain bouncing onto the walls above the DPC therefore the gap should be substantial e.g. about a foot. I would ask building control what a suitable gap should be.

[moustachebandit]

herewego said:

moustachebandit said:

Unfortunately the decking will sit above the DPM due to the levels and the way the house is constructed. All I can do is leave a decent gap between the house and the decking so water isnt able to collect against the brickwork above the DPM.

As I understand it the issue is rain bouncing onto the walls above the DPC therefore the gap should be substantial e.g. about a foot. I would ask building control what a suitable gap should be.

Having done some research it looks like if I leave a 5/10 mm gap between the ledger and the wall then that should be sufficient to prevent damp. However I may think about installing something like this between the house and the deck

http://i.ytimg.com/vi/aF2mJye12s4/maxresdefault.jp...

Should help with UFV and also limit any potential issue from rain splash (but think I might be over thinking this!)

[Camoradi]

herewego said:

As I understand it the issue is rain bouncing onto the walls above the DPC therefore the gap should be substantial e.g. about a foot. I would ask building control what a suitable gap should be.

Am I missing something, or does the rain not hit the walls above DPC pretty much every time it rains anyway?

[drmotorsport]

Camoradi said:

Am I missing something, or does the rain not hit the walls above DPC pretty much every time it rains anyway?

No your correct, but some people think rain bouncing off the ground is a double whammy and a bit too much. If i was that concerned then i would be painting on some kind of transparent tanking maybe!

[herewego]

Camoradi said:

herewego said:

As I understand it the issue is rain bouncing onto the walls above the DPC therefore the gap should be substantial e.g. about a foot. I would ask building control what a suitable gap should be.

Am I missing something, or does the rain not hit the walls above DPC pretty much every time it rains anyway?

This issue is covered by building regulations which is why I suggested contacting them for the skinny.

[Camoradi]

herewego said:

This issue is covered by building regulations which is why I suggested contacting them for the skinny.

Thank you. Sorry I should have explained I was asking because I am facing a similar situation. I'll have to think of a solution too

[SAB888]

Camoradi said:

Am I missing something, or does the rain not hit the walls above DPC pretty much every time it rains anyway?

Exactly! More likely the outer skin will get wetter through driving rain hitting it.