Help understanding my floor

[tiarocs]

We have builders currently ripping out an old kitchen. When doing so, they took up some tiles; sound more red square tiles underneath, took those up and then said they’d reached clay soil. They’re saying we need to dig out the concrete completely, and then put a membrane and insulation down.

Is this the right approach for our house? I’m worried that we may encounter other issues but unsure what the “right” way to sort this issue out is.

I’ve attached some photos of the floor. You can see a trial pit (that’s for the removal of the wall), and can see the general construction of the flooring.

Any thoughts or advice on how to proceed would be so welcome.

Thank you

 

[tiarocs]

Can anyone point me to the best standards for victorian solid floors?

 

[stuart45]

Have you looked at limecrete?

 

[tiarocs]

Have you looked at limecrete?

No, never heard of it. Total newbie and first renovation on the house … is it what I should be looking for on the floor?

 

[stuart45]

Scroll down the page a bit and look at a recent thread called' damp at bottom of wall'. Having a DPM installed in an old house where it doesn't tie in with the DPC has been known to cause damp at the base of the wall. Limecrete allows moisture to breathe out gently over the floor surface. It isn't cheap though, so it's up to you if you want to take a chance on having a DPM.

 

[tiarocs]

Scroll down the page a bit and look at a recent thread called' damp at bottom of wall'. Having a DPM installed in an old house where it doesn't tie in with the DPC has been known to cause damp at the base of the wall. Limecrete allows moisture to breathe out gently over the floor surface. It isn't cheap though, so it's up to you if you want to take a chance on having a DPM.

Thank you for this.

My brother in law is a surveyor so I just had a chat with him. He says if the DPM is installed properly and tied into the DPC we shouldn’t have any issues with the work. Is that your understanding too?

 

[stuart45]

Getting it tied in to the DPC is a key point. Has it got a DPC. Could be 2 courses of slate.

 

[Lacan07]

Thank you for this.

My brother in law is a surveyor so I just had a chat with him. He says if the DPM is installed properly and tied into the DPC we shouldn’t have any issues with the work. Is that your understanding too?

Ask him how he proposes to retrofit a DPM into a double skin solid brick wall. I'm genuinely interested to know.

 

[tiarocs]

Getting it tied in to the DPC is a key point. Has it got a DPC. Could be 2 courses of slate.

Yes it does have a DPC

 

[Lacan07]

Scroll down the page a bit and look at a recent thread called' damp at bottom of wall'. Having a DPM installed in an old house where it doesn't tie in with the DPC has been known to cause damp at the base of the wall. Limecrete allows moisture to breathe out gently over the floor surface. It isn't cheap though, so it's up to you if you want to take a chance on having a DPM.

I think there is slightly cheaper version of the limecrete floor isn't there? My mind has gone blank, something to do with breathable glass beads?

 

[tiarocs]

I think there is slightly cheaper version of the limecrete floor isn't there? My mind has gone blank, something to do with breathable glass beads?

Glasscrete?

 

[stuart45]

I think there is slightly cheaper version of the limecrete floor isn't there? My mind has gone blank, something to do with breathable glass beads?

Are you thinking of foamed glass?

 

[tiarocs]

I guess what I’m really asking is - it was fine, does it even need to be changed? The builder says yes. I’m certain the damp we have is due to outside ground level and damaged pointing. On that, they want to use a lime cement mix, should it just be lime?

 

[housewinnie]

I would not add a dpc. Limecrete it again and let it breath.

 

[elizabeth]

The cheaper option and less labour is for a hybrid floor using glass foam beads as Lacan07 suggests, around the perimeter about 15cm deep and 20cm wide.with a geotex membrane and a lime mortar on top level with the middle of the existing concrete floor.
Cement added to lime is not a good practice. The permeable nature of lime to release moisture will be affected. The lime mortar around the bricks allow moisture to be wicked away from the wall through sun, wind, and atmospheric pressure. If using cement mortar or lime/cement mix, the bricks can retain moisture and overtime become weak and lose their faces.
Having said that you may find lowering ground levels is the answer. It’s probably best to get other members advice as it’s a big job.

 

[tiarocs]

Ask him how he proposes to retrofit a DPM into a double skin solid brick wall. I'm genuinely interested to know.

He said he’ll cut out the mortar, and tie it in…

 

[tiarocs]

I would not add a dpc. Limecrete it again and let it breath.

It already has an original dpc (house built in 1897)… it’s a dpm they’re proposing (tied into the existing dpc)

 

[Lacan07]

I guess what I’m really asking is - it was fine, does it even need to be changed? The builder says yes. I’m certain the damp we have is due to outside ground level and damaged pointing. On that, they want to use a lime cement mix, should it just be lime?

Yes, if there's no sign of damp I'd be tempted to leave as is and concentrate on the high external ground. Throwing a bag of lime into a cement mortar mix is a classic builders trick to keep the customer happy, its usually hydrated lime from the builders yard. The pointing should be lime only. I would go with an NHL lime mortar rather than a lime putty based mix. That way you'll get a quicker, trouble free set and a bit of extra strength. It comes in powder form in bags, just add water. Get a 2 or 3.5.

 

[Lacan07]

He said he’ll cut out the mortar, and tie it in…

That's the theory, what's the method? Rather him than me!

@stuart45 have you ever seen anyone attempt a retrofit?

 

[stuart45]

That's the theory, what's the method? Rather him than me!

@stuart45 have you ever seen anyone attempt a retrofit?

I've worked on jobs where its been done. There's different methods. Cutting out a groove into the joint and bending the DPM into it next to the DPC is quite tricky, especially at the corners. Cutting it off just above the DPC, and using a sealant behind is easier. As I was working for firms at the time I can't say whether or not it worked.
A DPM wasn't part of the regs until the mid 60's, so most people living in houses built pre this won't have one in their concrete floors. The majority probably don't have damp issues. A lot depends on the ground conditions. Whether the subsoil is free draining, how high the water table gets, underground springs, leaking pipes, condensation etc.