# Forum Home Renovation Cladding  Bolting timber to concrete  stumps

## Hkdave68

I want to bolt timber onto oldish concrete stumps. Some stumps have no holes and I'm not too keen to use dynabolts as i don't want to damage the stumps. Any ideas?
Thanks
Dave

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## Snipper

You can't use any type of anchors let alone drill a hole through concrete stumps as the majority are not designed to take it.  Many years ago by luck and chance I got the stumps delivered to a job with holes already in them at regular intervals.  Never seen or heard of them since.  They saved so much stuffing around attaching timber cleats to the side for baseboards only having to bolt them.   
The way I do it is use a U shaped folded steel bracket made by using 30 - 50mm  x 2mm thick (might be 1.8mm?) gal steel plate custom guillotined from a steel fab business at about 450mm long. Can't find them for sale anymore so have to make them myself when required.  Fold them up yourself in a vice so the bottom opening width of the U is the thickness of your stump and timber cleat combined.  Eg 100mm stump + 90 x 45mm timber cleat = 145mm. fold the 2 sides at 90 degrees at a right angle to the bottom keeping the opening size at the bottom to 145mm. The remaining two sides folded up will both be about 150mm long.  Drill a hole about 110mm (based on 100mm stump depth) up from the bottom of the U at 9mm diameter on both sides.  This is to accommodate a 150mm  minimum x 8 mm gal bolt, nut and washers.   
The steel brackets are wrapped around the stump and the glued on 90 x 45 mm timber cleat you wish to attach by bolting through these holes which are positioned at the back of the stump and out of the way.  Used with a combination of polyurethane glue makes an exceptional permanent clamp to attach the timber cleats without affecting the structural integrity of the often poorly constructed concrete stumps.  Can use one clamp down pretty low, above ground level and then attach the top of the cleat to the bearer or joist if your building inspector/certifier allows.  
Many others do a similar job using hoop iron and screws and occasionally a tensioner but is not as solid as these bolted stump clamps.  Much cheaper though as the home made stump clamps will cost you around $3 - $5 each including the bolt + a bit of your time. Polyurethane glue costs about $12 tube but will be much better than liquid nails in this situation.

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## Hkdave68

Ok thanks. Also what width battens do people use? I am thinking cut down fence palings? 
thanks 
Dave

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## Snipper

Sorry but not sure what you are referring to as a batten.  I usually would use 90 x 45 treated pine as the stump cleat .  Being the timber clamped to stump so then baseboards fix to this.   Baseboards can be anything really but most common is 150 x 25 mm rough sawn treated pine.  Also used as a paling fence plinth.  Have also used different types and sizes of decking and also colorbond steel fascia.  You may be governed by fire restrictions depending on area.

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## ringtail

Really common to fix into concrete stumps up here Snipper. They are 200 - 250 square and take a chemset anchor no worries at all. Just don't drill too close to the edge. As long as one drills in the middle it's all good. Chemset is a must. No expanding anchors.  
Hk, most just use a hardwood fence rail as the batten on the stump. Sizes vary but use treated hardwood and don't sit the batten down on the ground. Give it 75 mm minimum clearance for termites. Seal the end of the timber with bitumen or diesel or paint.

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## Hkdave68

Thanks everyone

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## Snipper

> Really common to fix into concrete stumps up here Snipper. They are *200 - 250 square* and take a chemset anchor no worries at all. Just don't drill too close to the edge. As long as one drills in the middle it's all good. Chemset is a must. No expanding anchors.  
> Hk, most just use a hardwood fence rail as the batten on the stump. Sizes vary but use treated hardwood and don't sit the batten down on the ground. Give it 75 mm minimum clearance for termites. Seal the end of the timber with bitumen or diesel or paint.

  
Wow.  Never heard of stumps that size,  thats one thick and extremely heavy stump.  Anything over 1.2m from ground needs 125 x 125mm concrete stumps or timber but the majority of stumps are just 100 x 100 concrete sometimes made at the local concrete/ mini mix plant with left over concrete that could be any strength.  15mpa blindings or 35mpa high strength.  Lucky dip most times.  Very easy to crack the longer ones so like handling glass. Once cracked No good. Range from 0.6m - 1.8m.  They have a mild steel  6mm rod embedded through the centre for minimal reinforcement and the tie down point. 
You'd need a crane to put yours in as the 125mm ones are very heavy.  250mm x 250mm! holy jesus!.

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## ringtail

Been used for at least the last 80 odd years up here.  Brisbane House Stump & Steel Supplies | Products

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