How to make a hearth for a woodburner in the shed?

I pointed out you don't know the regulations you threw at me....?

Talk about a U turn :-D:-D:-D

Read on.......

Spider farm! :-)

Might be a pain to sweep clean too?

Smooth surfaces best imho...

That last is a requirement?

I don't believe my hearths beneath my stoves ever get above 100deg -does yours?

A small stone outbuilding I am fixing up to be reasonably warm and dry as a workshop / office / store. The floor is concrete poured onto a polythene sheet onto the earth floor. I am going to fix 2x1 battens to the concrete with some polystyrene or something between them and lay softwood t&G floorboards onto the battens. about 40-45mm in total height. I want to have a hearth in the corner for a possible woodburner if the space is used as an office.

I can do wood but I am not so good with sand and cement, so how do I make an attractive 4' x 4' hearth? Stone paving slabs? tiles? old bricks? they would all do, but how do I do it? Do I start with a timber frame around the area? Can I put any insulation in? vermiculite? Thermawrap? What do I put under the slabs or quarry tiles to make up the height? What do I bed them down on? and how do I make the joins? The heat from a stove - will it crack stone? or cause other distortions?

Advice appreciated

Tim W

My suggestion to do it cheaply would be 3x2 2" thick high density concrete paving slabs as the base with the same or slightly nicer ornamental stone flags on top. They don't object to heat once dry.

My own wood burner sits on a slate hearth. About 1cm thick on concrete.

The woodburner in our lounge - already fitted when we bought the place - sits on imitation York stone paving 50 mm thick, with mortar between the stones. It is about 1500 x 800 mm overall. One of the joins has a narrow crack along just about all its 1500 mm length. I must say that although it serves a purpose, I've never thought the stones were particularly attractive.

I wondered if for your purposes, to avoid mortar, you could build a wooden frame to hold block paving (as used for drives and patios), and if you needed to use fine, kiln-dried sand to hold them in place.

Probably the cheapest way is to set-up a form (which can be any shape you like) and pour a concrete hearth: use extra fines in the mix and float the top to give the finish you want, or add a self-levelling screed layer, or investigate concrete polishing. Alternatively just bed paving slabs, bricks, a piece of slate - anything that won't burn or crack - on mortar. To state the obvious: whatever you do needs to be built off the slab, not over any insulation.

No worse than anything else in a shed, and I doubt they like all that heat for too long. Well, they don't hang around in the BBQ when I fire that up! :-)

I can tell you that mock York stone with all its uneven surfaces is a pain to keep clean! Block paving isn't too bad to sweep; I was just trying to follow the OP's wish to keep away from cement.

Tile cement and sand and cement grout.

Lay the tiles first, then build a frame with a gap so you can infill everything with grout or sand and cement.

Tiling is a matter of tapping the tiles down onto a cement bed nice and level using a level, with a regular gap, and keeping cement off the face, then when set and the surround is built, using sand and cement or grout to fill between everything with lots of wet rinsed sponge to remove excess grout/cement.

I don't have any objection to cement. I just don't have much experience of it. Don't know what you mix it with, how you calculate the quantity, anything like that.

TW

Thanks. That was far from obvious to me.

My slab has timbers set into it to fix battens to, so I see we would be breaking the rules to have a 50mm hearth on top, timbers having to be at least 250mm below the hearth. Surprising! TW

The insulation (sh/c)ould have gone under the floor, sandwiched between two layers of polythene. The one on the ground is the DPC, the one on top of the insulation is necessary if you use open-cell insulation like expanded poly. 'Celotex' or extruded poly wouldn't need this. Some strengthening like weldmesh or heavy guage galvanised fencing like the stuff used to keep sheep in probably a good idea.

Most woodburners don't heat the floor up that much, assuming they up on legs, so no need to go mad with a full-on 5 inch concrete construction hearth that you would need for an open coal fire (see Part J).

Am thinking I will lay 32mm paving slabs onto the concrete, then finish with natural stone floor tiles, or quarry tiles around 10mm thick. All fixed with soft adhesives - PVA, rubbery or gripfill type things - to avoid the heat breaking joins. That will bring the height comfortably close to the wooden floor.

Thanks all.

I shouldn't worry too much. Look at the specs for some of the stoves you're thinking of using, para 2.23a of the regs will probably apply.

As others have said, what about some insulation in the floor? I can recommend "secondsandco" for "second quality" Kingspan at good prices (no connection).

Another comment: had you thought about a floating floor, rather than nailing boards to battens?