Fixing joist wallplate to thermalite block - help !

[Cabbyfan]

Hi,

Very keen to get my new floors in this weekend. Joist hangers on wallplate thrubolted to walls.

New gable is in concrete dense blocks so used Fisher 10mm throubolts all good.

Came to fix to party wall and disaster, fixings wont grip and tighten.... block is like cheese so im trying to find a suitable fix so buioding control will sign off on Tuesday.

Any suggestions?

 

[Cabbyfan]

thnking chemical route...
http://www.screwfix.com/p/fischer-fip-300sf-polyester-styrene-free-resin-300ml/23386

 

[Doggit]

We've done this one recently, but I can't remeber the thread. He cut a slot in the thermalite blocks with an angle grinder, and used the chemical route to fix the joist hangers in, and the job worked perfectly.

 

[John D v2.0]

Our builders drilled holes and put a threaded rod in each hole with some resin, then tightened the nut up the next day.
Those blocks are about as easy to fix in to as a rice crispy cake.

 

[Doggit]

Those blocks are about as easy to fix in to as a rice crispy cake.

Exactly, you can fit a rod with chemical resin, but the nature of a thermalite block means that the chemical resin will then turn if you overtighten the nut. Joist hangers are used on thermalite bocks, and the downward pressure holds them in place. But you need a solid one, not the strap type.

 

[Newboy]

http://www.screwfix.com/p/fischer-fis-v-hybrid-mortar-resin-360ml/88507

Make sure you drill accurately and prep properly.


http://www.screwfix.com/p/rawlplug-hole-cleaning-pump/6995f
http://www.screwfix.com/p/rawlplug-hole-cleaning-brush-8-10mm/1275f


http://www.fischer.co.uk/PortalData...trate-reports/documents/Thermalite_Report.pdf

 

[^woody^]

You should have used hangers in the wall. Bolts in those blocks are crap for loading.

You don't need resin and you don't need tight bolts as the plate is not going to pull out, the loading is vertical.

You would get a better fixing using something like window a anchors, as they work slightly differently and the sleeve expands to hold the screw better.

 

[Cabbyfan]

thanks chaps. will let you know how i get on !

 

[Ian H]

Also, if you haven't already bolted that timer in place. I found it easier to nail the hangers on first so you can do the hard work on the floor and get them wrapped round the back.

 

[Cabbyfan]

Quick update, fixings signed off by building control woohoo ! Unfortunately my 8 x 3 C16 timber joists I have stacked outside are all banana shaped grrrrr.. Been on site less that a week, not happy.

 

[Doggit]

8x3s. What sort of span or distance on the joists have you got.

 

[Ian H]

Extra noggings will pull them straight.

 

[Cabbyfan]

Hi, longest span is about 3.8m but they are big joists, was specd by the architect.

Extra noggins might not fix all of them, a length of 3.2 has a deflection of nearly half its width and a lot of them are twisted too..

 

[tomfe]

Are you doing 600mm centers with a floor full of baths?
If they are no good send them back.
But you'll find that most cheap mass timber is like this unless you are first to a new pack and pick your own. Or have a relationship with your bm who know you'll send any rubbish back.
I'd check to see if you can use 8x2 ( a more usual size for that span)

 

[Ian H]

Oh, that's not good. Some of mine twisted slightly but didn't bend. They were 8x2's over 3.3mtrs.

I clamped the next lot together in 6's until it was time to use them.