Replacing joist without taking up floor

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Grendel
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Replacing joist without taking up floor

Post by Grendel »

Just to add as a note rather than a suggestion but there have been times when we’ve jointed timbers together with scarf joints of one sort or the other . This has been in situations where the aesthetics were important and sisters or steels were considered unslightly. I mentioned cutting a slot in a beam , that too has been in a situation where the finished look was important too. The steel fitted into the beam and bolt heads sunk in too and covered over if the beam was thick enough. Sometimes voids might be filled with resin . As I say these ideas aren’t really suggestions as they involve a lot more work and thus cost a lot more just a bit of interest hopefully.
Anyway good luck with however you proceed and perhaps revisit this thread with pictures after you’ve done the job…
dewaltdisney
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Replacing joist without taking up floor

Post by dewaltdisney »

Talking of scarf joints did you see that wedged scarf joint in the joist in the photo G?

DWD
Grendel
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Replacing joist without taking up floor

Post by Grendel »

No I didn’t and to be honest viewing it on my phone I’m still not sure . In the first one I thought I was looking at a shadow 😡
lsx
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Replacing joist without taking up floor

Post by lsx »

Hi all

So here’s an update on where I’ve got to…

I have 5 joists with rotten ends to repair/replace. The first two are only approx 1.2 metres long, so I’m just going to replace the whole joist in their case. The other three are 4m long and I intend to repair those with bower plates.

In terms of replacing the two short joists, so far I’ve:

Removed the skirting from the area in the room above

Removed a couple of bricks from this same area to gain access to the wall cavity. The property has a cavity of approx 200mm although it’s not a ‘real’ cavity with ties, rather there are large pieces of stone bridging the outer/inner leaves every so often.

The joist pockets are formed from pieces of stone mortared into place. As well as this, the ends were packed (to the sides and behind) with random stone and mortar. I’ve removed all of this so if I wanted to I could now slide the joists approx 160mm further into the wall. Hopefully removal and replacement should now be straightforward*.

I’ve levered the floorboards up using wooden wedges, and have then been able to use a multi tool with a heavy metal blade to cut the nails. There was a learning curve to this in terms of cutting the best shaped wedges - I settled on a 10 degree angle of length approx 180mm, made from some old joist section that was lying around.

Amazingly when I hit the first joist I need to replace, it moved!! They aren’t magically fastened down after all.

Joist pockets formed from pieces of stone:
IMG_0025.jpeg
IMG_0025.jpeg (542.83 KiB) Viewed 131 times
Random rubble around joists:
IMG_9996.jpeg
IMG_9996.jpeg (438.09 KiB) Viewed 131 times
With the stone and rubble removed:
IMG_0021.jpeg
IMG_0021.jpeg (467.08 KiB) Viewed 131 times
Wider view:
IMG_0023.jpeg
IMG_0023.jpeg (591.79 KiB) Viewed 131 times
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lsx
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Replacing joist without taking up floor

Post by lsx »

I just have a couple of things I was hoping someone could help me with?

If the existing joists are 7 and 3/16” in height and 3 and 1/16” in width - so approx 184mm x 75mm, am I best to go for new timber or reclaimed?

And in terms of trimming the replacement joist to match the existing, what do you call the following cut? It’s like a notch in the underside..
IMG_9856.jpeg
IMG_9856.jpeg (248.59 KiB) Viewed 129 times

I really appreciate the time you’ve all taken to help me this. Your advice was awesome :)
Grendel
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Replacing joist without taking up floor

Post by Grendel »

Always good to hear back how a job is doing , thanks for that .
New or reclaimed timber ? If you’re going to reinstate the ceiling then it doesn’t really matter and for that matter unless you’re going to sit down there admiring the joists I don’t think it really matters . New is likely to be treated but probably not the same size , smaller in all likelihood. Reclaimed is likely to be closer in size if you can find some although probably not perfectly and it’ll be untreated so you may need to price in some treatment . Incidentally joists were commonly 3” thick as the cut nails could split thinner timbers especially if they were in a straight line.
That notch , it might have some fancy name but to me it’s just a notch…
Wedges , long and shallow . Ever so often we’d cut a shedload as the masons were always after them …
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