Concrete floor in late-Victorian house - unusual?

blue_max_3

retsinelg said:

I don't think I understand the difference, sorry? First time buyer with absolutely no knowledge of property and DIY...all I did was prepare myself by reading as much as I could but I probably have a lot of useless knowledge and not enough relevant stuff in my head

What is the difference between screeded and concrete and which is more common? Is screeded generally better than concrete?

Screed is more like mortar. Concrete has larger stones in it. If you have to dig both up, the concrete will be massively more work. Screed is often laid over concrete though.

SameOldRoundabout

Our house is from around the same time, the hallway is partially Minton tiles and partially painted concrete (original!), a thin layer of less than 30mm laid directly onto earth. It’s collapsed so needs digging up and ideally filling with limecrete. Our surveyor was concerned about damp levels in the joists under the suspended living room and dining room floors due to previously blocked air bricks and advised we fill the lot in. Maybe this was what happened at this house. 

Doozergirl

I've had a glass of gin that has had a disproportionate effect on me but this thread is full of misinformation. 

Taking a damp meter around the house is not a good sign of much.  It can help when you definitely have damp, but it doesn't diagnose it and it's used by people who don't understand it and sell expensive 'fixes' (read disguise) for it when it could have been fixed for very little money at all.   In many cases, they make it much worse. 

Many Victorian houses didn't have suspended wooden floors at all.  In most cases, they were earth or ash (as someone has already pointed out) and at some point someone has gone all 20th century on it and relaid it in concrete with a damp proof membrane. 

It CAN be an issue for damp because old houses were made to breathe.  If there is excess water underneath the house for some reason, it gets driven around the plastic membrane and up the walls, usually showing on internal walls that are covered on both with gypsum plaster that doesn't breathe either.  

You shouldn't replace Victorian floors with concrete,  but with suspended floors it's a no-brainer because it's cheaper to address the source of damp ingress and replace the affected joists, even if it's all of them! 

Damp does not just happen, however.  It seems to hold some sort of mystery for RICS surveyors who don't want comebacks so they let other people at it with plastic and 'guarantees'.    

retsinelg

Doozergirl said:

I've had a glass of gin that has had a disproportionate effect on me but this thread is full of misinformation. 

Taking a damp meter around the house is not a good sign of much.  It can help when you definitely have damp, but it doesn't diagnose it and it's used by people who don't understand it and sell expensive 'fixes' (read disguise) for it when it could have been fixed for very little money at all.   In many cases, they make it much worse. 

Many Victorian houses didn't have suspended wooden floors at all.  In most cases, they were earth or ash (as someone has already pointed out) and at some point someone has gone all 20th century on it and relaid it in concrete with a damp proof membrane. 

It CAN be an issue for damp because old houses were made to breathe.  If there is excess water underneath the house for some reason, it gets driven around the plastic membrane and up the walls, usually showing on internal walls that are covered on both with gypsum plaster that doesn't breathe either.  

You shouldn't replace Victorian floors with concrete,  but with suspended floors it's a no-brainer because it's cheaper to address the source of damp ingress and replace the affected joists, even if it's all of them! 

Damp does not just happen, however.  It seems to hold some sort of mystery for RICS surveyors who don't want comebacks so they let other people at it with plastic and 'guarantees'.    

I guess it's actually quite probable that it was earth or ash before given it was definitely a feeder house for the local factory so I assume fairly cheaply constructed. That's good information though as it makes more sense to me, somehow, that you might then put concrete on it - even if, as you say, it's not always a good idea. I guess I couldn't get my head around why someone would swap wood with concrete, but perhaps that's my modern tastes.

Yes - the thing about those houses being constructed to "breathe" is what I'd heard and was basically my only info on concrete floors - that they create damp in old houses. I'm glad to hear that's not always the case though, and there was no visible sign or smell of damp in the house (of course, there are ways to cover it up....) so I think I can stop panicking at every bit of news 😂

SameOldRoundabout

Yes - the thing about those houses being constructed to "breathe" is what I'd heard and was basically my only info on concrete floors - that they create damp in old houses. I'm glad to hear that's not always the case though, and there was no visible sign or smell of damp in the house (of course, there are ways to cover it up....) so I think I can stop panicking at every bit of news 😂

I wouldn’t worry that much, we’ve found about 6 reasons causing the various damp issues in our house since moving in only 3 months ago and fixed them all. Reasonably confident now that the damp issues are gone and won’t return. Without doubt the worst one has been caused by a leaking window which previous owners decided to badly patch rather than fix, and then used gypsum plaster and filler all below the window to cover the damp patch. When we removed it last week we’ve had to hack ALL the plaster back to bare stone to dry it out as the gypsum had just trapped all the moisture in the wall! These houses really do need to breathe where water is concerned, but find the cause and the problem is fixable. 

Dampnerd

The main concern in this instance (with regards to dampness) is what we call “wicking”. Within modern new build properties the damp proof membrane within a solid floor is continued and built-into the structural brickwork to provide a continuous barrier against dampness. 

In previous times this was not the case and indeed when new solid floors are laid within existing older properties rarely if at all is the membrane cut-into the wall but simply lapped-up it.

With the exception of new build properties therefore there is a weak and vulnerable joint where the solid floor abuts the walls providing a passage for moisture to pass through even if there is a damp membrane in the floor.

If and where the internal wall finishes are in contact with these weak and vulnerable floor/wall joints they have a tendency to act like a wick and draw moisture upwardly into them.

Resolve is easily achieved by removing the skirting boards and trimming the wall finishes behind them upwardly circa 50mm to ensure isolation any remove any risk of absorption. 

The then created isolation gap will be concealed once the skirting boards have been replaced.

New and/or existing skirting boards should be treated on the back and bottom edges using a wood preserving paint/chemical such as Cuprinol 5 star.

As a previous poster has mentioned, given the age of this house, it will almost certainly have a slate damp proof course. Contrary to belief physical damp proof courses rarely if at all fail unless the property has suffered for example significant movement which causes them to break and subsequently become incomplete. Moisture by-passing them is normally due to building defects commonly high external ground levels and external renders or indeed “wicking” causing them to become bridged.
As doozergirl has pointed out, I don’t recommend you go buying an electronic moisture meter and sticking it in the wall arbitrarily. They are incredibly sensitive and without knowledge and experience you will frighten yourself at what sort of readings you might get back! I doubt your RICS surveyor will be able to give you much more than he already has. Consider paying an independent remedial surveyor to make a visit, this way you will be given completely impartial advice without being sold a product. There are some good independents who live in your neck of the woods. I’m in London so too far!