Direct to "Earth" timber floor

[Borderer]

Hi.
Sorry if this has been done before, I am new here and can't find on search.
Just bought a 1780 (approx) cottage the sittingroom floor is timber which has been laid on joists which lie direct to earth
(Well really a gravelly stoney mix) the floor is pretty dry reading mostly under 20% and the only sign of any rot is where there has been a leaking heating pipe.
I have been reccomended to dig all this up and replace with a concrete, DPM insulation layer.
To me this seems unnecessary
If the floor has been dry for a few hundred years then why should it be replaced.
What do you all suggest.

 

[formerly known as]

I would leave it alone. A new floor as described would result in damp walls. I would however check that ground levels are lower externally than internal (subfloor level where the joists sit) and that there is some air movement. I would also check that rwg's downpipe is going to a soakaway of some sort rather than washing into the subfloor void. Oh, fix the plumbing ....................... :lol:

 

[Flyfisher]

I have been reccomended to dig all this up and replace with a concrete, DPM insulation layer.
To me this seems unnecessary
If the floor has been dry for a few hundred years then why should it be replaced.
What do you all suggest.

Who recommended ripping it all up and replacing anew?

Seems to me you have the right instincts and are asking the right sorts of questions - don't fix what ain't broke!

Fix any leaking pipes, ensure rain water is being properly dealt with and the underfloor void is adequately ventilated (as mentioned above) and settle in to enjoy your new house.

Oh, and welcome to the forum.

 

[Tony.]

How would the dpm work?

 

[Borderer]

Good question
As I see it a DPM would localise any damp that would normally escape from th whole floor area to the perimeter.So unless the walls have a DPM fitted and tied in to the new DPM all you are doing is shoving more damp into the base of the walls
As I said the floor is not really damp at all. All drainage etc is good and the ground levels are all good.
Interestingly the house is part of a terrace but was originally built on its own. It seems that the adjoining houses have full thickness walls so there is at least 6 ft of wall between the houses.

 

[Tony.]

Leave it alone.
Ensure the leaks are fixed, and if anything add some extra airbricks to increase under floor ventillation.

 

[MatthewC]

Welcome to the forum. You've come to the right place.

Just bought a 1780 (approx) cottage ....I have been reccomended to dig all this up and replace with a concrete, DPM insulation layer.

Whoever recommended that is in the wrong place!

To me this seems unnecessary
If the floor has been dry for a few hundred years then why should it be replaced.

Your instincts are right - IF you have to dig it up then you would want to lay a limecrete floor which is breathable, but from the sound of it even that might be unneccesary.

Photos and more details of the house, please?

Matthew

 

[Keithj]

I hear the recommendation to add DPM and concrete to period properties often enough that my eyes roll.

It cost me a scary amount of money to repair the damage done by a builder who thought concrete was a good idea. If you really want to see what happens, take a look at this boring blog from a few years ago.

 

[MatthewC]

There was another example last night on one of those TV property programmes - Homes Under the Hammer I think. A couple bought this damp old listed cottage in Cornwall and when the presenter asked what they intended to do, the chap replied "lift all the floors, lay membrane and DPC", whereupon I switched over. :roll: :roll:

 

[SilverSaloon]

timber which has been laid on joists which lie direct to earth
(Well really a gravelly stoney mix) the floor is pretty dry reading mostly under 20% and the only sign of any rot is where there has been a leaking heating pipe.
I have been reccomended to dig all this up and replace with a concrete, DPM insulation layer.

Why fix a problem that doesnt exist, even if there was a problem, concrete would not be the answer.

Ignore anything else that comes from the person who recommended this!

Fix the leak; enjoy the house as it was intended.