Probs ventilating suspended floor

[SiH]

Afternoon all you knowledgable folk

We have an issue with damp in our house, and as part of it are having to replace a rotten suspended floor.
The house is a late 19th century cottage, brick built, double skinned (non cavity), and doesn't appear to have a damp proof course of any sort.
There don't appear to be any foundations (and we don't have the budget for underpinning) but there are no subsidence issues.
The floor is level with the ground on the exterior of the building.

The floor in question is in our dining room - It currently only appears to have one sub floor vent - I suspect this is the cause for the underfloor damp.
We are about to get quotes for replacing the joists, and doing the boards ourselves to save a bit of money. However, we have an issue in that I can't figure out a way to sufficiently vent under the floor, so fear that the new floor will just rot away again.

I have drawn an amazing paint illustration below if the issue we have

Untitled

• SiH
• 10 Oct 2011
• 1

The room concerned is the light grey dining room. The issue is further confounded by the fact that there is a section of solid floor at the back of the room(marked in dark grey) - we're not sure what to do about this. I'm concerned digging it up may unsettle the house.
As you can see, there are very limited places to place addtional vents - in fact, I can't find anywhere to put 'conventional' ones. Are there any alternatives that we can use? Forced ventilation? Some sort of non intrusive periscope vent?
I'm presuming that we can't bring up a vent on neighbouring property.

I'm at a dead end with what we could do, so any help is much appreciated!
Thanks in advance
Si

 

[freddiemercurystwin]

How much is the void? Why not do a solid floor and eradicate any future ventilation issues. That may be the simplest solution.

 

[SiH]

The void is currently filled with rubble, and looks to be ranging maybe from about 6/7ft deep, to about a foot at it's shallowest.
I'd thought about a solid floor, however the problem is that nowhere else in the house has any form of damp proofing due to it's age. My concern is that a solid floor with the requisite DPM would force moisture elsewhere - to the other solid floors, and the walls, which already have an issue with damp (which I believe may be related to the sub floor ventilation, and a previous attempt to treat the walls with some sort of sealing paint).

In addition, the house is in an area which has historically flooded (although the house itself has escaped) - I'd be concerned that a solid floor would make it vulnerable if this hapepned again.

 

[Nige F]

And the best solution - you can add insulation to near modern standards - and a damp proof membrane plus conduits or even underfloor heating Just read you next post re damp walls - a solid floor won`t contribute to the damp walls - you probably need to bite the bullet and treat the walls @ the same time as a new floor is laid OR if you do want a wooden floor you need to speak to the neighbour for access to their land to cut in some airbricks to your walls

 

[SiH]

Cheers muchly for the input.

I think I may be opening a huge can of worms here, but I know there's the huge debate between returning a house to 'as is' to let it 'breathe', and installing modern materials.
Depending on who I talk to, some people are tilling me to go solid, and some stick with suspended in order to ventilate under the floor. In my mind I'd prefer to go with the 'breathing' course of action - for this reason I'm currently looking into lime plasters for the interior finish.

I've read articles by and spoken to quite a few people who have suffered 'migration# of damp to the walls after fitting a solid floor in an odler property, and that's my big concern.
To be honest, another part of the driver is that I'd love to retain as many of the features of the house as is possible, and one of them is the suspended floor.

Cost is an issue (isn't it always) but if something pricier is the best solution, we'll just live on gruel for a bit longer!

Apologies if this comes across as me saying 'no, I'm right' - that's not the case, at all, I'm just trying ot look at all avenues and read as much as I can - I'm not a builder, and my humble IT geek mind tries to explore every avenue before procrastinating extensively and then making a decision!)


Just noticed tha tyou said about airbricks - What would be the considered 'norm' for these? would it be to have a sort of 'periscope' type affair so it came out in the wall, or would it be to have a vent that tunneled and came out level with the floor on their proeprty? The former I can see would need a massive chunk of wall work I'd guess? And the latter would possibly need deeds and legal stuff?

 

[theoldun]

Geeky. Have read both your posts and can possibly give you a solution, but need further information.
1. Will your neighbour allow you access over his garden for a day to fit new vents? 2.Size of existing floor joists? 3.Are they built into external walls? 4.Are they sitting on sleeper walls? 5.Size of dining wall? 6.Width of concrete slab in lounge? 7.You must determine whether you have a DPC.
Hope you did not have to pay your DPC specialist, as we would not give you tuppence for his comments.
oldun