Can I remove a block from an underfloor dwarf wall?

Our has has a one block high crawl space which I can access via a hatch on either side of the house. In the past I have managed to use to draw cables across our house from our router to a home office. However the space under either hatch is very small (about 2m square) and I would like to be able to access other areas of the house.

The sub floor dwarf walls (is that the right name?) are one block high. Under the first hatch it looks like this:

And under the second is this:


Would it be safe to remove one block on either side to allow better access? The 5 wide joist doesn't appear to be bearing any significant load from above but I would obviously avoid the blocks below it, what other advice would you give me in choosing a block to remove? Most of the dwarf walls have either walls or stairs above them.

Going along the house (parallel to the floor joists) rather than across it the walls do not have ventilation spaces. Other than making it harder to remove the wall would this change the feasibility of removing a block?

Avoid the one with the five joists but no problem removing the right hand one. If you sense a bit of extra movement of the joist/floor you could add a temporary/removable strut under the wall plate below the joist.

Could you perhaps manage to squeeze through, by turning two adjacent blocks round 90 degrees, so the still are able to provide support where the joists are located?

jeds said:

Avoid the one with the five joists but no problem removing the right hand one. If you sense a bit of extra movement of the joist/floor you could add a temporary/removable strut under the wall plate below the joist.

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Thanks, That's what I thought. The strut idea is a good one.

Harry Bloomfield said:

Could you perhaps manage to squeeze through, by turning two adjacent blocks round 90 degrees, so the still are able to provide support where the joists are
located?

Click to expand...

The joists centres are around 30cm so I think it's a touch too narrow for that to work and leave space for my shoulders. Do you have an idea for getting a block out intact?

slangivar said:

Do you have an idea for getting a block out intact?

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A car scissor jack would make taking the weight off the blocks quite easy.

If moving blocks 90 deg does not allow enough space to get through, I would be buying some lengths of 70mm heavy steel angle iron - that sat across two blocks to span where one was removed, would work. This way up L along side the timber with maybe a couple of screws through into the timber to prevent it moving.

I was worried you were going to say that. Most of the gap between blocks is only about 4cm wide, but I suppose bashing a couple of extra cms off the end of the block to get a jack in will be much easier than bashing the whole block out. Especially in such a narrow space.

Are those blocks set on cement? Difficult to tell in the photos.

A long lever (thick steel pipe or similar), using a stack of bits of timber as the fulcrum would work well enough, to allow you to turn a block through 90 degrees.

I think they might be set in cement. I'll get a pinch bar down there sometime and see what moves.