18mm ply/sterling board? fixing 2x4 to concrete ceiling

[chalkythebrave]

to set the scenario: i am building a climbing wall in a large, disused basement. this involves making a frame of 2x4 and attaching it to the walls and the ceiling. The walls are ok, they are secure. The ceiling, however, is giving me grief.

It is concrete and about 18in thick, however above the ceiling are some law courts that i don't really want to disturb. The concrete, although strong, is a bit holey in places.
What is the best way to attach 2x4 timber to this ceiling? I've tried drilling a hole and using a screw with a plug but i don't really trust the structure to hold me. Somebody mentioned using "Injection Resin" to secure a threaded bolt and then attaching the 2x4 onto this. would this work? is there a cheaper option?

is this picture a bad idea bearing in mind there will be 3 of these holding up a board of 5ftx8ft 18mm and a grown man frolicking around?

And my other query, how much weaker is sterling board than 18mm ply? would it snap if there were beams across it and i jumped up and down? more so than ply?

thanks for any help.[/img]

 

[big-all]

heeelllooo chalkythebrave and welcome

you show a bit of wood at an angle how long is it unsupported !!!!

how far apart are they!!!

definitely go for 18mm ply for the sake of an extra £10

ply comes in 8x4 and 10x5foot[usualy special order in all but the largest wood yards]

 

[chalkythebrave]

the wood is just over 4ft long, the width of an 8x4ply.
I was planning on 3 such supports, one at the start, one in the middle, one at the end of the board.

 

[chalkythebrave]

 

[big-all]

not enough
i would aim for support every 2ft so you would have to connect the centre of your triangle to the wall ceiling intersection assuming its at 45%

you will also need them 2 ft apart

have you considerd old scafold tubes running to the floor !!!

the trouble with drilling into concrete is gas electric water sewage and reinforcing rods can get in the way

 

[big-all]

just seen your picture

you have supported it properly on the wall then where it needs maximum support you are trying to reducing it to a minimum

 

[Deluks]

If you can bolt some hefty timber off of the walls you could put joists across, as if you were building a floor, and swing everything else off of that.

 

[chalkythebrave]

big-all: the problem with free-standing scafold poles is that they hurt when you fall on/into them. there will be a load of mats below the wall to fall onto, but i don't want any metal to nock my noggin on.

about the amount of wood needed, i agree with you. i'll fix another two supports in.

I am still a little worried about how i've connected into the concrete. somebody mentioned "Injection Resin". i imagine that the procedure would be to drill a hole into the concrete, fill the hole with injector resin and then put a threaded rod into the whole and bolt that into the wood. good idea? (ignoring potential problems with pipes in concrete)

 

[big-all]

the idea of scaffold poles was they are behind the boards can extend several feet behind before returning to the floor and still be very strong

i can comment on resin anchors as i have never used them but i do think you will be drilling around 6 inches into reinforced concrette without knowing what services and steel bars are in the way!!

are those concrette beams or rsj coverd over under the roof !!!

 

[Symptoms]

Chalky - what ever method you adopt to fix the timber ends into the concrete your basic structure appears to be missing critical elements; namely the struts which 'close' the triangles at ceiling level. You need to add these by bolting them to the sides of the existing structural members. By adding these horizontal bracing struts you also provide additional fixing points to the concrete - failure to add these will result in an excessive load being placed on the single fixing points in your original proposal.

Hire a decent hammer drill, say a SDS Max, and use bolt shield anchors (sometimes called ragbolts or rawlbolts). Decent/secure mechanical fixing provided by these things would give me more confidence, whilst hanging upside-down, than 'resin' anchors.

Over engineer this setup if other people are going to use it 'cos if it collapses and somebody get hurt you'll have to explain yourself to our 'learned friends'.