Listed Building - whole new floor due to damp

[Bettie]

Hi, I have just bought a small listed 2 bed cottage. One of the rooms on the ground floor has had bad damp and the whole floor needs replacing. Apparently it’s been unlived in for 2 years.  There are 2 options in the picture below, please can anyone tell me a rough cost to get either options carried out. I’m in Hertfordshire. I’m trying to do the budget for the renovation but this is one area I’m not sure on. 

Thank you ! 

[PeterW]

Why do they want to use limecrete..? And why the Newton layer on the walls ..? Is that a retaining wall ..??

 

Damp needs ventilation or non-porous materials. If it is truly damp - and you want to retain a floorboard finish - then consider putting in a suspended floor with insulation between the joists and allow the underfloor to breathe with cross ventilation and air bricks. 

[Bettie]

Thanks Peter, that sounds great. These are the suggestions from the surveyor 2 years ago. Instead of doing the suggested work the owner left the property empty and are now selling it. Would you know how much it would cost to put in a suspended floor with insulation between the joists and allow the underfloor to breathe with cross ventilation and air bricks in 11m2?

Thank you. 

[Bettie]

it is not a retaining wall. I am not sure about the Newton layer. 

[PeterW]

11sqm is tiny - you could DIY it. 
 

What are the other ground floor rooms like..? Are they suspended or solid ..?

[Ferdinand]

A couple of general points.

 

Have you or predecessor taken the outside ground level down to a sensible place? That makes a difference.

 

When we first moved into ours as a family a long time ago, you could see a damp "tide mark" on the walls at about 7ft, and detect it with a moisture meter ? .

 

The floor joists were laid directly on he earth.

 

Will the listing authorities let you put air bricks in?

 

[Bettie]

Thank you for your help!

 

In the survey it says that Kitchen and bathroom (both downstairs) have concrete slab, it's only the front room that has timber.

It also says the ground level is approximately 150mm above internal floor level. There are no air bricks. It says that the cement plinth and sunken pocket had been covered and/or filled resulting in significant rot to the ground floor timbers. I can't see any request to the council to put air bricks in.....

[PeterW]

28 minutes ago, Bettie said:

It also says the ground level is approximately 150mm above internal floor level. There are no air bricks. It says that the cement plinth and sunken pocket had been covered and/or filled resulting in significant rot to the ground floor timbers.

Right, so first thing is to get digging outside if you can ..!! Get the soil away from the walls, get at least 150mm below internal floor level and then back fill that with coarse clean gravel. That will stop water coming through the wall. 
 

Joists can be replaced like for like but you need to sort the sleeper walls they sit on. It sounds like you would be better off replacing the floor with insulation and a concrete slab with a decent DPM lapped up the walls. 

[Bettie]

Brilliant, thank you ! Would you have any idea how much this might cost and do I have to use a listed buildings builder ?

 

Thank you. 

[PeterW]

It depends - what is the grading and what is listed ..??

[Bettie]

It is grade 2, it’s a terrace of about 5 houses and I think each whole house is listed. Thank you.