Mega Heavy Live Edge Mantle Piece

SeanoChuinn

Hello everyone,

I'm trying to put up a "floating" mantle piece at home which has a significant amount of weight to it. Probably breaking the 60kg mark, but that's a complete guess. It's a piece of cut Beech see picture below:

https://ibb.co/9sx87Kv

It's been in the house for nearly 4 weeks now so has dropped significantly in weight. The fireplace has 2 hidden columns either side of it made up of three glued and screwed 9x2 timbers, which were a part of the house timber frame. This is what I'm hoping to attach the mantle to on either side:

https://ibb.co/1QpnThy

Everything has obviously since been slabbed and hard walled so all covered over now. The fireplace will never have an open fire, so not worried at all about fire protection. There will obviously be sanding and leveling required, with all of the difficulties working with live edges and getting the back flush to the wall. I'm really just concerned about getting it secured.

So, I've been thinking about two parts of this in particular that I'd love to get some advice on,

1. Is what type of brackets to use. I've seen a lot of one's on Amazon and elsewhere that slide into two pre-drilled holes (more for floating shelves) and then screwed to wall, but I fear the weld would not be fit to hold the weight. I've also considered flat right angled brackets that'd I'd router into the timber to hide then screw and secure into wall. But again I don't know if the weld at the angle would hold the weight.
and
2. What type of screws would be best to use to get the best grip on the 9x2's. I'm thinking some sort of lag screw type deal to get enough grip on the 9x2's.

I'm open to all suggestions, was hoping to avoid having to put 2 sides to this to hold it up, but may be left with no choice given the weights involved. Thank you everyone.

Four Phucs Ache

As nice as it is, the mantle you have is what you want to portray as being solid once fitted.

To retrofit this with its current dimensions with the wall structure you have is a mountain of work and quite frankly expensive.

Me?... remove as much mantle material as possible from the back/ wall face to create a 1 maybe 1.5 inch diameter open ended box that will seat against the wall. Large diameter flat wood drill bit required , chisels and time.

2 reinforced steel angle brackets into the block at the fireplace, ideally the block face steel longer than the mantle support.

Maybe theres a way/ system available but 60kg is a big ask into those timbers.

Lumen

60kg is nothing for a couple of pieces of wood to take in compression. Think of how narrow a walking stick is.

You could put in some long lag screws into the framing timber, cut the heads off, and epoxy them into holes in the mantle.

If you drilled at an angle you'd barely need the epoxy as the mantle would just slide down onto the bolts.

As lumen said 60kg isnt a whole lot for wall fixings.
I dont know how good your woodworking is but french cleats (metal ones) could be an option .
You'd have to router pockets into the mantle.

dathi

https://www.ebay.co.uk/itm/Moisture-Meter-Damp-Meter-4-Pin-MD-Digital-Wood-Moisture-Meter-Handheld-Humidity/153881215455?hash=item23d40901df:g:BzgAAOSwnP1et1FZ

the first thing you should do, is you should buy a moisture meter, as if it is a freshly cut piece of timber it will be any thing around 30% water and it will twist and shrink as it dries

GreeBo

Lumen wrote: »

60kg is nothing for a couple of pieces of wood to take in compression. Think of how narrow a walking stick is.

You could put in some long lag screws into the framing timber, cut the heads off, and epoxy them into holes in the mantle.

If you drilled at an angle you'd barely need the epoxy as the mantle would just slide down onto the bolts.

Will it be compression though? The mantle will be cantilevering away from the wall. (Though thats not really an issue for a couple of bolts as already said)

Drilling at an angle would complicate the install in my opinion, much easier to get things wrong.

@OP How high up are you planning on putting it?
I'd probably be more comfortable fixing to the blocks rather than the studs, but I dont see any issues either way.

If its not so high that you cant see underneath it then it opens up your options for both the fixings but also how you might prevent it from sliding off.

Calahonda52

Post a picture of the FP as is, no point is looking at the substructure.
Also, what length of that piece will you be using.
In addition, never lighting a fire in a fully functioning fireplace does not exempt you from the fire regs from a selling perspective.

The One Doctor

How are you finishing it? Lots of options there, would require lots of work though.

CJhaughey

How long ago was that live edge board milled? It looks very green to me and I would be inclined to leave it for a bit longer to stabilise or you may find that whatever you do to fit it at the present time may end up being worth nothing if it warps and twists out of the fasteners.
Don't under estimate just how much pressure a drying piece of wood can apply, its much stronger than you might think.

Lumen

GreeBo wrote: »

Will it be compression though? The mantle will be cantilevering away from the wall. (Though thats not really an issue for a couple of bolts as already said)

Yeah, but the leverage is quite small as the centre of mass is only a few inches away from the fixing.

It would need to be some dodgy framing for that to pull out!

GreeBo

CJhaughey wrote: »

How long ago was that live edge board milled? It looks very green to me and I would be inclined to leave it for a bit longer to stabilise or you may find that whatever you do to fit it at the present time may end up being worth nothing if it warps and twists out of the fasteners.
Don't under estimate just how much pressure a drying piece of wood can apply, its much stronger than you might think.

The OP says its been in the hose for 4 weeks, I'd hope it was milled long before that, but would agree it looks a bit green, the bark is still well on.

@OP you want about a year drying per inch of thickness..

SeanoChuinn

THANK YOU everyone for coming back to me. This is savage. Sorry for the late response but here goes...

@Lumen I've considered the lag bolt option and taking off the heads alright, my fear with that is getting everything completely square and level. Have to be a dry run for that option. What epoxy would you recommend?

@Greebo It'd be level with the top of the existing mantle here which is 1.3m up off the floor to bottom of mantle piece. So sitting down you still wouldn't be able to see the bottom of it and definitely not standing up looking at it.

@Brownfinger I've used french cleats before for tool hanging in the shed (wood ones) but not sure if I'd trust them here?

@Calahonda52 that's a great point about future owners. The house is passive standard, air tight etc. so if there was a fire place going into it, either by ourselves or future owners, it'd have to be a closed air tight unit so no naked flames near the mantle. No sure where that would leave us with fire regs but get where you're coming from.

@CJ It would have been cut as a tree about 2 months before I got it, was milled about 12 weeks ago, but has only only been indoors now probably 4 weeks. It would have gotten plenty of weather prior to being milled and brought indoors, I'm happy to hold off for longer, even much longer, to allow for full drying and movement which might and probably will eventually happen. @Greebo at 1 year an inch thickness means we'll have it up by the time Covid passes us by :P

@Doctor I'm really just looking for a very simple finish. I've put up some book shelves with live edges in the past and even though it's a little amateur, they do look good - I think anyway . I finished them with just a simple clear varnish allowing the wood to somewhat pop out and speak for its self. Once it gets another few weeks (or months) indoors I'm hoping to strip off the bark and hopefully have some nice natural wood stain and colors exposed underneath.

These are the natural shelves I put up and this finish is exactly what I'm going for. Nice and simple.

https://ibb.co/XXLL2z5

Definitely LOTS of hard work involved, but that's all a part of it.

Here's a picture of the finished FP right now, measurements included

https://ibb.co/fXF7GMn

The mantle is currently 25mm wider than the green strip you see there to allow for shrinkage. I'd hope to have it go 1.7m across the fire place which roughly works out about half way between the fireplace and windows on either side. That green strip is 160mm wide. Currently it's 1.8m long so 100mm coming off of it would certainly reduce it weight wise a little more.

Thank you again everyone.

Lumen

SeanoChuinn wrote: »

I've considered the lag bolt option and taking off the heads alright, my fear with that is getting everything completely square and level. Have to be a dry run for that option. What epoxy would you recommend?

You can use a drill guide for the pilot holes, which you could make yourself. As long as you flip it to use opposite directions for the wall and mantle, and use it the same way for both sets of holes, all four holes will be perfectly parallel.

I would probably use Araldyte two part epoxy because it's what I'm used to.

If you put the bolts within about 40mm of the bottom edge then if things go horribly wrong you can cut the bolts with a multi tool.

The other option which is a bit more woodworky is to use a full bolt in a recessed hole and then fill the hole with a dowel which you cut flush with a flush cut saw, x2.

SeanoChuinn

Thanks Lumen. A lot of the problem here is confidence in my own ability to get everything dead right . And I know it'd have to be for this to fit perfectly onto bolts or whatever I use. Being out a couple mm's could make a HUGE difference when trying to fit it.

OK call me crazy, but I was thinking...what if...

On the back side of the mantle I draw a defined rectangular box, leaving say 50-60mm all round to the outside edge and removed the wood within this middle piece? This would reduce weight and possibly give me more options to fix something more regular possibly, a 4x2 or bigger, to the wall. Then worry about fixing the mantle to that in that newly formed cavity at the back of the mantle ? Am I crazy?

Lumen

Yeah, you could make a big cleat (male), bolt that to the wall and then glue a (female) recess in the piece to that with some idiot proof gap filling adhesive like Gorilla glue.

If the test fit isn't perfect you can adjust with shims or make another cleat.

Do you have a router to make the recess? Otherwise I guess a spade bit and chisel.

Class MayDresser

Instead of a 4*2 timber "insert" to receive the hollowed out mantlepiece would you consider 40mm square slotted unistrut fixed horizontally just short ofthe full length of the beam, both with anchors into the block work and screws into your glued 9*2s?

6 M8 hexhead bolts tightened into M8 zebedees within the unistrut through countersunk holes in the front of the beam, and just fill or dowel them in after?

On the phone but Google unistrut and you'll get an idea of what I mean, used in industry for carrying trays with heavy loads of cables or ventilation piping.

jack of all

I'd avoid fixing to both the timber framing and blockwork- shrinkage and differential movement will just cause cracking somewhere. How about getting two 18" or 24" lengths of unequal steel angle, weld two steel bars (19mm dia or 25mm dia.) to the side of the long leg and bolt each bracket to the side of your studs. With the weld on the long leg of the angle you get plenty of weld length. Bore two (slightly oversize holes (or oversize holes with bushings inserted) in the mantle beam. offer up and slide onto the protruding bars. Maybe put some timber noggins (and oversheath with ply) between the built up studs to stiffen the lot up. If you're worried about timber shrinkage and movement (I would be) incorporate a shadow gap around your mantle- either route a 6x 10mm rebate around the top and ends where it meets the wall or do a detail in the plasterboard. Movement will happen best to try and incorporate it into the design. With my steel rods and bushings idea it offers you the option to remove the mantle if it doesn't work out or if you change your mind.

Calahonda52

SeanoChuinn wrote: »

..

@Calahonda52 that's a great point about future owners. The house is passive standard, air tight etc. so if there was a fire place going into it, either by ourselves or future owners, it'd have to be a closed air tight unit so no naked flames near the mantle. No sure where that would leave us with fire regs but get where you're coming from.

...

To maintain th PH standard the stove will need to be sealed with an external air feed.
FRegs don't distinguish between naked and dressed flames:D

In terms of mad ideas how to fix it, to reduce the risk of warping, you could think about two bars epoxied, level and horizontal, into the blockwork joined by a piece of steel plate, welded, which would then slot into a deep long mortice cut in the back of the piece. This cut would be the thickness of the steel plate with two holes drilled to allow the two bars in
To hold it in place you could have predrilled holes in the plate that could take either wooden dowels or SS pins from underneath.
The bars/steel plate would be pre-made off site so the rest of it would need some careful setting out.
If you wanted the option of taking it off, you could sleeve the bars in to some pipes epoxied into the block work that maybe protrude 50mm into the timber and have a steel dowel through the bar/pipe at each end.
All doable with care and planning.
Pls post a picture of the final solution, by next weekend maybe

SeanoChuinn

Calahonda52 wrote: »

To maintain the PH standard the stove will need to be sealed with an external air feed.
FRegs don't distinguish between naked and dressed flames:D

There is a hidden, sealed, external air inlet pipe under the flooring alright Calahonda. The option is there for us, or others, to install a "passive" air tight type stove in the future if required.

As for pictures next week... I'll do my best

Lots of viable options to consider anyway, I'm definitely better informed than I was. Time is on our side at least, as I'm anxious to make sure it's left as it is for as long as possible to allow for maximum moisture loss.

Hopefully in another few months I'll get those pictures up!! Thanks again everyone.

Class MayDresser

My understanding was it's slabbed and plastered now, or is it all still open?

keithdub

If the wall is solid brick l would cut out the plasterboard and drill 3 or 4 25mm holes get some 2 part epoxy (fischer) is the brand I use. And get some rebar and seat them into the wall. And transfer the measurements of the rebar onto the timber and epoxy the rebar into the mantel

SeanoChuinn

Class MayDresser wrote: »

My understanding was it's slabbed and plastered now, or is it all still open?

No it's closed up now, there is a picture of the setup at build time and a picture of the FP now included in earlier posts Class.

I will be removing some wall board to expose the back end, but I will have to be very careful here as there is an air tight membrane to consider, so any holes I make or drill will need to be patched to maintain that air tightness.

keithdub

The 2 part epoxy should be frealy air tight and a role of air tightness tape to cover everything up. You should be good with that

SeanoChuinn

Yeah, we've used various types of Siga tape throughout the house depending on the various surfaces we're working on and resealing. Just need to be careful and limit tears or unneeded holes

charlesanto

https://www.laoisstone.com/images/Mantel-beam-installation-instructions1.jpg