Edwardian house, flooring surprise - not a good one !!!

[dazlight]

I’ve put ardex NA and DPM1c on floors like that over the years with no failures that I know about. But as I tell the clients it’s always a risk and to dig up an new subfloor is the best way.

 

[Deleted member 174758]

I have seen a mixture of asphalt and ballast used only a few times, but the solution agreed with the client has invariably been to break out the floor as Dazlight says, in part because nobody would guarantee their DPM on top of it

 

[ianleon]

Thanks for taking the time to read this and reply.

Looks like i'm going to have to bite the bullet and go for it !

I shall get a pro in to do the concreting but I'm sure I can do most of the prep work.

Just a few questions before I start;

Do I break it all the way down to the earth ?
What is best to put down and at what depths to prep for the concrete ? (hardcore, insulation,etc)
With new builds i'm pretty sure they put the DPM into the brick course what am I best to with the edges ?
And also as its probably like it through the whole bloody house how do I go about joining the concrete and DPM with the adjoining rooms ?

Sorry if they are basic questions but this is obviously not my speciality !

I have a 2 week window before i'm back to work (key worker) so it would be nice to really get this room forward.

Thanks in advance for your replies.

 

[dontbelieveawordofit]

if it’s part concrete and part suspended , then theyve probably just concreted the rotten bits in over the years. this prevents effective ventilation under the house and exacerbates rising damp .
if it was my house, i’d remove the concrete room by room ,fit 6” wall plates and reinstate the original suspended floor using joist hangers . also inject a chemical dpc in the mortar bed at floor level to help prevent rising damp . you can lose the broken up concrete underneath. cheaper , cleaner and allows the ventilation and movement that the build of your house intended.

 

[JohnD]

if it's wet under there, the cause is often a plumbing leak. Do you have a water meter? Or sharp ears?

Chemical injections do not add ventilation, or cure leaks, or repair building defects.

 

[dontbelieveawordofit]

as for rebar internally ? that’s way over the top and completely unnecessary unless you intend building solid walls on top of it.

 

[ianleon]

if it’s part concrete and part suspended , then theyve probably just concreted the rotten bits in over the years. this prevents effective ventilation under the house and exacerbates rising damp .
if it was my house, i’d remove the concrete room by room ,fit 6” wall plates and reinstate the original suspended floor using joist hangers . also inject a chemical dpc in the mortar bed at floor level. you can lose the broken up concrete underneath. cheaper , cleaner and allows the ventilation and movement that the build of your house intended.

I can't be 100% at this point if it ever was a suspended floor.

I know in one of the back rooms it is part suspended part concrete and that room has air bricks, I suppose i'll find out when i gun it up ?

 

[ianleon]

if it's wet under there, the cause is often a plumbing leak. Do you have a water meter? Or sharp ears?

Chemical injections do not add ventilation, or cure leaks, or repair building defects.

The issue i originally had was the floorboards where nailed to the concrete which had damaged the already broken up bitumen DPM hence the floor boards where starting to rot where they were nailed down and some where they butted up to the wall. I have a slate DPC which does look in good order.

 

[dontbelieveawordofit]

a slate dpc is as good as anything else.

 

[dontbelieveawordofit]

if it's wet under there, the cause is often a plumbing leak. Do you have a water meter? Or sharp ears?

Chemical injections do not add ventilation, or cure leaks, or repair building defects.

a common sense suggestion to stop rising damp. nothing else.

 

[JohnD]

There was a weird square in the centre with a hole in:

It seems unlikely in your house, but I've seen buildings of similar age where an iron pillar was inserted to support something above (very common in houses that were opened up for a shopfront), and a big steel bolt is often used to bolt down safes, to prevent Burglar Bill dragging them away to open in his workshop.

 

[Mr Chibs]

I confronted this same issue, house of a similar age.

I chose to dig up the old concrete back to soil, add/unblock air vents, build some sleeper walls and put in a suspended wooden floor, with insulation.
Mine were around 3 to 4" of old concrete and various hardcore/soil/ash underneath.

It was a lot of work to do... do I regret it... no, it's way warmer and I know it will last ages.
Un-insulated concrete floors are always cold.

Good luck, keep us up to date.

Chibs

 

[bobasd]

J&B, You noticed
a "mixture of asphalt and ballast"on the OP's floor.
This, of course, is commonly known as Tarmac & has been mentioned on here by others and myself as occasionally composing residential floors.
The fool trolls on here were almost psychotic with excitement in their ignorance that such a substance had been used in domestic interiors.
Well mouth foaming dont go far where construction realities are involved.
Facts, not hysteria work best - as you J&K and one or two skilled others know.

 

[bobasd]

OP,
to find out if the floor was a previous suspended floor, simply go outside that room, and search at its exterior wall surface for air bricks?

 

[ianleon]

A little update.......
All broken up and dug out, amazing how quick you can fill as skip !
Now to work out what i'm going to put down.