Is this the probable cause of this room being damp

[RobertBM]

I just took up a floorboard in what is an 1960's extension (which is always damp with efforescence salts on inside of walls ) and took these pictures. Am I being paranoid or is what I'm seeing a bodge and most likely the reason it’s damp.

I’m no expect but to me it looks as if the DPC is just resting on the ground, it’s bridged by builders rubble.

I will of course remove the rubble. Should I also think about replacing the wooden blocks under the floor joists with brick and new DPC on top of that?

Any feedback would be appreciated.

Robert

 

[mcluma]

That is no rubble, that almost practical clean

I think you are lacking airflow, are there any air bricks

 

[Nige F]

Agree - I just cleared out my 1960's bungalow floor void and brought out 30 bricks, 5 lignacite blocks and 2 flexi tubs of small rubble, rotted wood and a "weights" packet that's just part of the house - and it smells of damp wood despite putting a load more airbricks in the o/s walls a year ago. Will I ever get rid of the smell? It comes out the airbricks when the wind blows. PS there is a putlog under the kitchen floor FFS. .Yes you could replace the lumps of wood with cut brick and more dpc- get a trolley jack under the floor and lift the joist a tad. You can't have too much airfow

 

[RobertBM]

Yes there are five large airbricks in the three walls of this room (18x12ft ). I would be surprised if circulation was the problem as I remember there was even enough breeze coming up through the floorboards to move the door when we had the carpet up.

 

[RobertBM]

Agree - I just cleared out my 1960's bungalow floor void and brought out 30 bricks, 5 lignacite blocks and 2 flexi tubs of small rubble, rotted wood and a "weights" packet that's just part of the house - and it smells of damp wood despite putting a load more airbricks in the o/s walls a year ago. Will I ever get rid of the smell? It comes out the airbricks when the wind blows. PS there is a putlog under the kitchen floor FFS. .Yes you could replace the lumps of wood with cut brick and more dpc- get a trolley jack under the floor and lift the joist a tad. You can't have too much airfow

This is definitely the cleanest part. If I look under the rest of the bungalow there are plenty of bricks and pieces of wood and enough rubble to fill a small skip. I reckon I’d have enough materials to build another bungalow if I recovered it all

Will definitely do as you say, which is jack up the joists a little to remove the block and replace them with brick and new DPC.

 

[^woody^]

The DPC arrangement under a timber floor has nothing to do with dampness or efflorescence in the walls

 

[RobertBM]

The DPC arrangement under a timber floor has nothing to do with dampness or efflorescence in the walls

My thought was the efflorescence wasn’t caused directly by this, but maybe due to too much moisture in the air. It is where this moisture is coming from which puzzles me. There are no external pipes, cracks in rendering or anything else which would alert me. It’s only one of the three walls in this room which is effected too.

 

[mcluma]

Moisture could easily come up from the floor, and .....

you room above is warm, the ground is cold...... result condensation.... therefore you need airflow to disperse the moist air. ensure you have air bricks at the front and back of the property

 

[RobertBM]

Moisture could easily come up from the floor, and .....

you room above is warm, the ground is cold...... result condensation.... therefore you need airflow to disperse the moist air. ensure you have air bricks at the front and back of the property

There are lots of air bricks all around the semi detached bungalow. Could be there is something under the flooring which is preventing the air to flow through properly. Doesn’t help that there is an old brick extension down the side and back of the property which wasn’t done to the highest of standards in the 60’s. I’ll be removing more flooring boards during my summer holidays so I’ll get to see more then.

 

[^woody^]

If you had an air flow or underfloor damp problem, then the floor would be rotting away before the room walls got damp.

White salts on plaster will not be efflorescence, and the cause will depend on its location and extent.

Or the plaster itself could be the cause.