Suspended floor ventilation—thick stone walls

[shanghaiman]

Evening. I'm hoping someone's had experience of this problem. The building survey for a property I'm looking at buying recommends that I install more vents to ventilate the underfloor space. Difficulty is, the wall that needs them is a good 600mm thick and made of solid blocks of a hard stone (it's not sandstone, that's for sure). Also, the ground level on the side that needs them is as high as the joists are internally, and the unventilated wall is a good 12 to 15 metres from the air bricks on the opposite wall so the air's got a long way to go.

I presume one way of sorting it would be to drill a dirty great core out of the wall above the joist level and then fit some kind of duct over a hole in the floorboards to where the hole comes in through the wall. Other than that, and this might just be a stupid suggestion because of the cold draught problem, but could I just cut a chunk out of a floorboard and screw a vent cover over it, to allow the stale underfloor air to circulate from the outside world to the inside of the house? Basically, does underfloor space need to be ventilated from the outside, or can it be ventilated from the inside?

I've even done a nerdy line drawing.

 

[freddiemercurystwin]

//www.diynot.com/diy/threads/air-brick-in-solid-wall-but-dropping-into-a-floor-void.334848/

 

[endecotp]

Has the survey actually found any dampness?
For how many hundred years has it not had sufficient vents?
Do you think the outside ground level has been raised? Might there be old blocked vents below the current ground level?

No you cannot vent the void into the inside of the property.

 

[shanghaiman]

That'll be a straightforward "no" to venting to the inside, then! Ta.

"Has the survey found any dampness?" Hard to say—it's been unoccupied and unheated over winter, so elevated moisture in internal plaster in some places might just be down to that - the surveyor recommended heating and ventilation to warm the walls up and let them breathe, but noted as a different point that there's no sub-floor ventilation to the rear of the building, only the front.

Yes, ground level looks as tho it might have been raised, but probably over a number of decades at least—it's 1870s build. If there are old blocked vents, presumably I could try to locate them by looking under the floorboards internally, then dig down and fit a vent externally rather than recess it into the solid stone of the wall?

 

[shanghaiman]

Has the survey actually found any dampness?
For how many hundred years has it not had sufficient vents?
Do you think the outside ground level has been raised? Might there be old blocked vents below the current ground level?

No you cannot vent the void into the inside of the property.

That'll be a straightforward "no" to venting to the inside, then! Ta.

"Has the survey found any dampness?" Hard to say—it's been unoccupied and unheated over winter, so elevated moisture in internal plaster in some places might just be down to that - the surveyor recommended heating and ventilation to warm the walls up and let them breathe, but noted as a different point that there's no sub-floor ventilation to the rear of the building, only the front.

Yes, ground level looks as tho it might have been raised, but probably over a number of decades at least—it's 1870s build. If there are old blocked vents, presumably I could try to locate them by looking under the floorboards internally, then dig down and fit a vent externally rather than recess it into the solid stone of the wall?

Read more: //www.diynot.com/diy/threads/s...ation—thick-stone-walls.475691/#ixzz4WgrEgh9S