Removing concrete floor and fitting suspended

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I’ve got a house built maybe 1900s ish

Half the house is suspended timber and the other half is concrete floor with no dpm or insulation under it

I’ve done two knock throughs and the floor levels are all over the timber side is nice and level but the concrete floors arnt

The concrete floor seem to have a bit rising damp going off the Lino I took up

I’ve dug the concrete out and now need to decide what to put back down

I’d much prefer to fit a insulated suspended timber floor to make it easier to run services and get some airflow through the damper side of the house

Is this a daft idea?
 
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Any idea why thete is concrete there? Is it maybe that the original floor was a suspended timber one (often evidenced by old pockets left in the brickwork below floor level) and went rotten? If so that may indicate a lack of underfloor ventilation. So, are there any air bricks in that section which have been blocked off?

Oh, and no, it's not a daft idea
 
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Any idea why thete is concrete there? Is it maybe that the original floor was a suspended timber one (often evidenced by old pockets left in the brickwork below floor level) and went rotten? If so that may indicate a lack of underfloor ventilation. So, are there any air bricks in that section which have been blocked off?

Oh, and no, it's not a daft idea

To be honest I’m not sure. Only reason I can think is the ground level at the back of the house was higher but I’ve dug this right back down to where it should be anyway to stop damp
 
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So long as there is some form of airflow you should be OK - if needs be install an air brick or two below the joist line.

As this is a solid wall building you'll need to ensure that the ledger (if you go that way) is treated timber and that there's something like a piece of DPM between it and the wall, as a minimum (to minimise moisture wicking) - using a 150 x 150 or a 100 x 100 heavy steel angle section would be a better alternative as it will never go rotten, but it is more expensive and more awkward to drill unless you can get the merchant to do it.

I'd recommend using resin anchors to fix your ledger/angle plate, M12 size (14mm holes) at about 800mm centres, rather than Rawlbolts which can be a bit iffy in old masonry. If using a timber ledger, pre-fix the joist hangers on the ledgers which makes the job easier.

To install anything long and heavy like this it is less work if you first fix a temporary length of 3 x 2 to the wall below the bottom of either the ledger or steel angle - this can be fixed with 2 or 3 brown plugs (7mm holes) and some 5mm screws and is just a temporary support which you can level up quite easily. The ledger or steel are supported on this temporary batten and held in place against the wall with two or three screws and some mudguard washers (or home made plywood "washers") whilst you drill and install the resin anchors and then left until the resin sets (20 to 40 minutes, or cup of tea and a butty time) at which point the nuts can be tightened, the temporary screws, washers and temporary batten removed and used on the other side.

Joists need to be C16 structural grade, centres depend on the type of sub floor you are installing.

Think that's most of it...
 
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