Ventilation shaft ?

[ChasHyde]

Hope someone can shed some light on this one!

1905 Semi, mosaic tiled hallway with stairs straight ahead, and 'best room' (suspended floor) off to left. Door threshold to best room is damp, mosiaic lifted and staining to floorboards.

Under the stairs is a pantry with a ventilation grille at the far end, under the bottom stair. I have removed the grille and vacuumed the pipe (4" glazed). The pipe bends towards the 'best room'.

I have put drain rods down the pipe, but have hit a solid end to it, I have tried a very thin rod, but can find no way through. The rods do not seem to be hitting anything very close to the door threshold. What was the normal way of terminating this type of ventilation under the suspended floor? Could I be hitting a joist with the rods?

Thanks for reading this, hope you can help me to solve the mystery!!

 

[Nemesis]

I have to say I haven't a clue - sounds a very odd arrangement - just bumping this back up to the top in case someone else can help!

 

[Penners]

You're obviously wondering whether this is some installation to carry ventilation from the void under the front room floor to the pantry. An interesting idea.

At what height is the ventilation grille in the pantry - above floor height or below?
Is the floor height in the pantry the same as in the front room?
What is the pantry floor - suspended or solid?
If the latter, do you think that is original?

In order to discover whether your probe is hitting a floor joist under the front room floor, the only method I can think of is to use your ears. Get someone else to do the probing and see if you can hear the point at which it strikes something. You might find it useful to use the old mechanic's "listen-to-the-engine" trick of placing a screwdriver or similar implement with one end pressed to the floor and the other end to your ear. An all-metal tool works better than something with a wood or plastic handle.

Do let us know what you discover.

 

[ChasHyde]

Thanks for your reply Penners. The pantry floor is the same height as the rest of the property, but has a lower section where the ventilation shaft is. Therefore the ventilation clay pipe is underneath the level of the suspended floor.

I haven't tried someone else jamming the rod in and me listening, but it is on my list of things to do.

 

[ChasHyde]

Mystery solved . . . it involved removing the threshold to the room with the suspended floor, and one of the bricks underneath it, this then revealed a hole that I have been able to push a rod all the way through to the pantry under the stairs. I have pulled through a rope with larger and larger articles on in order to clean the airway. I am very reluctant to try anything too big, as the thought of getting the darned thing stuck under the floor is a worry !!

I now have the problem of how to replace the threshold . . .

 

[Nemesis]

Sounds a very odd arrangement, but glad to hear you have at least sorted one problem, which, as you have discovered, invariably leads to another.

Or several.

 

[ChasHyde]

Another reason for removing the threshold was that the edge of the suspended floor was becoming damp just where it met the threshold. Having removed the tiles etc that butted up to the wood, I thought I would have a dry floor - but not a chance!
The damp reappeared, from the edge of the floorboards to about 3 inches into the room. The endgrain of the boards is now is now free of anything touching it, but the boards are getting damp - how? I have no idea, condensation? but the boards should not be that cold to cause moisture to condense on them should they?
The dampness is not that deep into the wood, a flash over with a heat gun gets it to go away, but it re-appears after a few hours.