Need ideas for dealing with concrete slab in middle of floorboards

Forums › Home Workshop DIY › Need ideas for dealing with concrete slab in middle of floorboards

Samandcharlotte

2 posts

Wannabe Geek

#224161 6-Nov-2017 08:43

HI, I have recently decided to lift the kitchen lino and refurbish the original floorboards. Unfortunately I have discovered a 1000x500mm concrete slab in one corner. Wondering if anyone has dealt with this before and/or am looking for ideas on how to either incorporate into the floor or make into a feature. Note the kitchen cupboards are built in so have to be worked around. Thanks.

nickb800

2716 posts

Uber Geek

Trusted

#1895794 6-Nov-2017 09:19

Presumably the base for an old coal or wood fire stove.

I think you're going to have trouble doing anything to it without getting the cabinetry out of the way.

You should be able to remove just that set of drawers, the end panel, and toe kick out from under the benchtop. Usually just a few screws around and perhaps some sealant on the edges.

What is the level of the concrete like relative to the floorboards - i.e. flush, lower/higher?

Broadly speaking I think your options are to demolish and patch with floorboards, grind and polish to make a feature (not a great look against the floor boards IMHO), or lay wood laminate/vinyl (concrete needs to be ground lower to make a flush finish)

MikeAqua

7779 posts

Uber Geek

#1895805 6-Nov-2017 09:48

I would: -

- Grind the concrete down to lower than the underside of the board;
- Build up to level with under side of boards with a self levelling compound;
- Find some floorboards from a demo-yard or similar to patch the gap.

It will look OK.

Or by a rug.

Mike

gzt

17122 posts

Uber Geek

Lifetime subscriber

#1895817 6-Nov-2017 10:15

Look under the house and see why it's there and how big.

Bung

6480 posts

Uber Geek

Subscriber

#1895841 6-Nov-2017 10:32

gzt: Look under the house and see why it's there and how big.

We have something similar. It goes down to dirt as it supported the weight of a fireplave and chimney. Two floor joists also sit on our block.

esawers

551 posts

Ultimate Geek

#1895846 6-Nov-2017 10:40

Same situation at our place

We ground the concrete down to below the floorboards, and then put new joists in, and patched the rimu floorboards.

Worst part was we had recently been under the house and laid the black plastic, but all the concrete was left under the house afterwards.

Dingbatt

6756 posts

Uber Geek

Lifetime subscriber

#1896139 6-Nov-2017 15:45

Wish we had one in our house. Our new front loader washing machine shakes the crap out of the whole house!

“We’ve arranged a society based on science and technology, in which nobody understands anything about science technology. Carl Sagan 1996

Journeyman

1186 posts

Uber Geek

#1896172 6-Nov-2017 16:05

Just paint the concrete a woody brown colour :D

Wise

Send money globally for less with Wise - one free transfer up to NZ$900 (affiliate link).

mattwnz

20155 posts

Uber Geek

#1896299 6-Nov-2017 18:22

Dingbatt: Wish we had one in our house. Our new front loader washing machine shakes the crap out of the whole house!

Our washing machine had a warning about that. They do have the potential to cause structural damage to a house according to the warning. Apparently you can help with this by using plywood on the joists. Y Our instructions may give some guidance.

Aredwood

3885 posts

Uber Geek

#1896545 7-Nov-2017 08:04

gzt: Look under the house and see why it's there and how big.

Definitely check this. Have seen quite a few of these slabs which are held up entirely by the wooden floor. Meaning not too hard to remove.

eracode

Smpl Mnmlst
8854 posts

Uber Geek

ID Verified

Trusted

Subscriber

#1896555 7-Nov-2017 08:28

If investigations reveal that it may be possible to break it out, one of these should make short work of it:

https://www.hirepool.co.nz/concrete-breaker-large-electric-13-20kg

Sometimes I just sit and think. Other times I just sit.

Samandcharlotte

2 posts

Wannabe Geek

#1896957 7-Nov-2017 16:42

Thanks everyone! Feeling a little more confident. Great suggestions.

Fred99

13684 posts

Uber Geek

#1897020 7-Nov-2017 18:01

Usually the concrete slab is set at least a few inches below floor level, then a mortar topping put in to bring it to floor level after the floorboards are down. That topping should be able to be broken out easily with a kanga. I've done it with a 3 way rotary hammer drill from Bunnings. To refit matching boards over, then don't attach them to the concrete. If it's in a visible area, stagger boards cut to fit between joists closest to and one back from where the pad was. This should draw less attention to the patched area. Multitool to square cut ends of boards in place. Drill before nailing. If it's t&g, then you'll probably need to cut back some of the tongues between boards - multitool also works fine for this. If the boards need to span more than 450mm or so, and there isn't depth to add a joist, I guess you could pack under with some timber to support the boards, but I wouldn't attach anything to the concrete as it'll stay put while the timber moves with moisture changes etc, and will probably split the timber and cracks will open up.

tukapa1

725 posts

Ultimate Geek

#1897195 7-Nov-2017 21:36

Dingbatt: Wish we had one in our house. Our new front loader washing machine shakes the crap out of the whole house!

+1. Although the missus seems to like it....

Our frontloader is heading out to the garage.