Regulations regarding wall and flooring

[RobertBM]

I have two questions regarding the demolition of an extension wall and building regulations. We have an extension which runs (9 x 6 metres) on the side and rear of our bungalow (in red) which is suffering badly from subsidence and damp. Our plan is to demolish the 9inch wall and replace it with a cavity wall. Although our architect says we don’t need planning permission to do this as we not increasing the footage, we do need to adhere to building regulations. It was not until I looked at the plans did I notice the architect has replaced the current raised wooden floor to a solid one.

The questions I have are:

1. Being as there is absolutely nothing wrong with the current flooring can I not leave it in place and integrate it into the new build, or would building regulations not allow it. By this I mean would I need to renew it?

2. Wouldn’t changing this part of the bungalow flooring (in red) from raised wood to solid not interfere with the current ventilation under the property given there will be very little through flow?

Any advice would be appreciated,

Rob

 

[freddiemercurystwin]

Really why don’t you ask your architect, we only have a snippet of all the required information?

Anyway what is the suspended floor supported on at present? The subsiding 9” wall? If the wall is subsiding I would have expected there to be issues with the floor too. But if there’s nothing wrong with the floor it does not need to be upgrade for the project to conform with Building Regs.

Changing that part of the floor to a solid floor in principle is doable and the venting issue could be overcome with appropriate pipe vents under the new sab – they’re a little Heath Robinson but do work. Though digging out the existing wall and for a new foundation would likely mean some serious built up ground alongside the new wall would be required which is not always a great start for a ground bearing slab, though that said the slab can just span onto the inner skin to prevent it dropping and in fact down this neck of the woods all ‘ground supported slabs’ are actually sat on the inner skin for this reason.

Presumably only the external wall is being replaced and the roof propped and retained?

 

[RobertBM]

Thanks for the quick reply.

Unfortunately our architect is a pain and trying to get him to answer a question takes weeks and even then he rarely comes back the a direct answer

Instead of my trying to explain what the floor is resting on I have taken a few pictures for you. The wall to the left is the wall to be removed. The floor itself doesn’t seem to be effected by the subsidence.

The cold flat roof itself is being replaced. The main reason being the old extension was originally built in two sections and the bit we are replacing has a slopped ceiling rather than flat like the rest of the extension. It’s been leaking on and off for the past 30 years too. Plan is to replace the cold roof with a warm one.

So it sounds like I can keep the original flooring as long as I bring it up to current standards. I’ll need to see what that is given I didn’t think much has changed regarding floor structures the past 30 years.

 

[freddiemercurystwin]

So what's that joist in your first pic supported on? Is that a masonry wall? Bit confusing tbh.

 

[RobertBM]

The joist is resting on wood which is itself on a concrete base. The bottom picture is of the same location but taken further back from the wall. So in the bottom picture the right joist (running parallel) is the same as that in the top picture. Hope that isn’t too confusing as I can be terrible for trying to explain things

 

[wessex101]

If you were propping the roof and just rebuilding the external wall you could probably have just got away with Building Regs for the new wall. As you are replacing the roof as well I would say they will treat the whole thing as a new extension. Not such a bad thing, you might as well bite the bullet and put in a new concrete slab floor and bring the insulation up to current regs, with vent pipes as Freddy suggested for the inner suspended floors. By the time you've messed around trying to insulate and ventilate the existing floor it would probably have been easier and cheaper to rip it all out and start from scratch.

 

[freddiemercurystwin]

Hmm, well if the floor can be retained without it compromising when the new foundation excavation is dug out then it should be possible to retain it, assuming it is sound. Sounds like a bit of an odd set up tbh. That said the joists are pretty shallow so not much insulation can be inserted between the joists whilst retaining good airflow, which you may as well do as the boards are up.

BTW if the roof is also being replaced then be cautious as technically I suspect you may need planning permission. Once something is removed it is no longer there and so PP is required to put something in that empty space and wraparound extensions require planning permission.

 

[RobertBM]

@wessex101
I agree, had the roof been built to the standard of the rest of the extension we would have propped it up and just rebuilt the wall.

For me it’s more about reusing materials rather than filling up skips with things which are quite adequate and have been for some fifty years. I will need to look into the cost of putting in a concrete slab into what is a large area. Going by the cost of Readymix for the wall foundations (£1200), I’m guessing it’s going to be far more expensive than a raised wooden floor.

 

[^woody^]

If this is a repair of an existing extension then you wont need any building regs for the replacement work, but only for the insulation to meet current standards.

 

[RobertBM]

Hmm, well if the floor can be retained without it compromising when the new foundation excavation is dug out then it should be possible to retain it, assuming it is sound. Sounds like a bit of an odd set up tbh. That said the joists are pretty shallow so not much insulation can be inserted between the joists whilst retaining good airflow, which you may as well do as the boards are up.

BTW if the roof is also being replaced then be cautious as technically I suspect you may need planning permission. Once something is removed it is no longer there and so PP is required to put something in that empty space and wraparound extensions require planning permission.

Removing the floorboards and inserting insulation would be my preferred choice, although not sure what the thickness of the insulation would need to be. As you say there isn’t a huge amount of room being as the joists are only about 4.5 inches high.

The architect keeps changing his mind on the PP issue, but this is again down to him not listening to what we want done. Being as he is the one submitting the plans to the council, I’ll just make I get to see the plans first.

 

[RobertBM]

Yes it’s is a repair, so that is nice to know. Thanks

 

[wessex101]

If this is a repair of an existing extension then you wont need any building regs for the replacement work, but only for the insulation to meet current standards.

I would love to be a fly on the wall when you have the conversation with the building control officer trying to justify complete demolition and rebuild including new foundations, new walls and new roof is a "repair."

 

[freddiemercurystwin]

Yes MR BCO, I'm just repairing the walls and roof.

 

[RobertBM]

 

[Nakajo]

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