Airing suspended floor

[SuffolkLad2017]

Hi first time post so please be kind

Just moved in to my first house, its a Victorian house and the floors are shown as below In my drawing, Iam worried by the lack of air flow to the suspended floor, and is fairly mouldy under there now as I've just put central heating in. Joists are in a good condition though
I thinking of Coletexing in between the joist 50mm deep to keep heat loss to a minimum
Any ideas on how to improve the air flow?
The house Is a mid Terrace

 

[John D v2.0]

Tricky, im assuming no way to vent out the sides due to next door, so the only other way would be up the chimney. That could work quite well to get a draught going

 

[KenGMac]

SuffolkLad2017, good evening, a happy new year and as this is your first post in here a warm welcome.

Now or your dilemma, which is not uncommon.

How about you retro-fit more air bricks under the door [if possible?] and adjacent to the right hand neighbours property?

But, even with the possibility of three air bricks a guaranteed air flow within the suspended area of floor can not be guaranteed, indeed there will be two "Dead Areas" in the rear of the suspended floor area to the right and left.

However if you do install a further two air bricks it will assist to a limited extent.

Your options are severely limited without a truly massive upheaval, of cutting chases in the concrete floors to the rear of the suspended floor area.

Lets see what the board has to say about the above?

Ken.

 

[SuffolkLad2017]

Thanks for replying
would insulating be a bad idea Iam guesssing it's getting a small amount of air flow through the gaps between the floor boards?

I Can't get another under door possibly could get another in the bay window

Not sure how I could use the chimney to vent?

 

[endecotp]

How deep is the void?

 

[SuffolkLad2017]

There is 170mm to the bottom of floor joist

 

[Blagard]

It is probable that the rear solid floors were put in as a later "improvement". When that is done the correct practice is to set ducts in to allow vents from the the rear of the suspended floor through to the rear elevation. So check that if you have not already. Otherwise the addition of more vents where you can get them is about all you can do.

If the rear solid floors have always been there then your floor has already stood the test of time and I would not be worried about it. Insulation between joists is a good idea to help minimise energy loss. So long as the underfloor circulation remains essentially as it was I don't see that should be a problem.

 

[John D v2.0]

We had a similar problem where a conservatory and perch were added and blocked the air flow to that side of our semi. As a result the timbers were not in perfect condition any more. We wanted to insulate but doing so is a really bad idea until you sort the damp out.
In answer to your chimney question, you can dig out the hearth if it's still there, or rubble in our case, then build the front up with an air brick each side under floor level and sealed to the room. Then you're drying out your chimney and under floor with the same draught.

 

[Blagard]

Bearing in mind the sub-floor is just 170mm below the joists, if the joists show any sign of decay you should consider making that floor solid. If you do that you want to make sure you get adequate vetilation adjacent to the chimney breast by means of ducting. That is to ensure you have the free air requirements for a solid fuel fire without the draughts. Using modern flooring construction you will be able to incorporate insulation at the same time.

Frankly I can't see a practical solution to "sorting the damp out", only adding air bricks in the hope it improves. You are never going to get the cross floor ventilation that is ideal but at the same time many have gotten away with what you have with no trouble. I know because I have seen literally hundreds. In cases where the floor does become a problem and no cellars are involved the solution employed was to make the floor solid. Retrospective ducts in the rear floors is also not recommended as you end up damaging the DPM and potentially introducing another problem. It is also no guarantee that problems with timbers will be resolved by the added ventilation.

Insulation between the joists will not do any harm if you want to do it. so long as you don't block the airbrickks in doing so. (Your airbricks could well be sited in the same zone as the joists)

 

[endecotp]

There is 170mm to the bottom of floor joist

You mean from the ground (concrete? earth?) to the bottom of the joist?

Filling it all in is an option.

 

[Blagard]

You mean from the ground (concrete? earth?) to the bottom of the joist?

Filling it all in is an option.

No I mean removing the timber floor entirely and building a solid floor.

 

[endecotp]

Blagard, my question was to SuffolkLad2017 not to you, hence why I quoted his post.

 

[Blagard]

Blagard, my question was to SuffolkLad2017 not to you, hence why I quoted his post.

Oh! - Was past my bedtime so missed that,