Concrete pillar into obsy concrete floor?

[swag72]

Now I have the pier top adaptor, I can start thinking about the pillar / pier. If I go down the route of a concrete pillar I have a question really.

As my obsy will be on a flat roof, we are going to reinforce it with 6 inches of meshed concrete first. Obviously going onto a flat roof, I don't have the option to dig a big hole to sink the pillar into. I was wondering then whether bolts or lengths of rebar drilled into the floor would be sufficient for the concrete to be poured into a tube? The rebar would then continue through the tube.

I think in an ideal world I'd be pouring the floor and pillar all together, but that's just not doable, so I will be looking at putting the pillar onto the already dry floor.

[beamish]

hope your purlings/joists are up to it !Obviously depends on the area of the roof but 6" of additional concrete will weigh a fair bit even before the concrete pier is put on plus mount, weights and scopes etc etc plus you of course !

As for the idea tho sounds okay

[barkis]

You need a structural Engineer/surveyer to look at what you are proposing here, or at least post here the full specs of the build.

The ground base, the height to the roof supporting the Obs, the walls thickness and foundations.

It seems a lot of extra weight is being added to the roof/obs base. Is the build a garage or some other outdoor building?

Have you another thread running on this S72?

Ron.

[swag72]

Thanks for your comments both. I do have 2 threads with pictures of where I am proposing to put the obsy.

here and here.

The flat roof is normal spanish build. Concrete pillars and brick infill for the walls and a concrete ring beam. The roof will be concrete beams with roof bricks in between the beams then covered over with concrete.

Underneath the flat roof is my summer kitchen and small bathroom. It is not attached to the house in any way, so no structural issues there.

The walls I am planning on building with brick, not sure how heigh yet, that was going to be decided once the pier / pillar has been done. so I can get them just a little higher than the scope. The bricks for building with be air bricks and for the roof I am considering double skinned perspex - Like people have on a conservatory roof sometimes in the UK.

[barkis]

Mmm!, I am not qualified to make an assessment of the loads involved, and I don't know how you stand as regards any planning rules and regs regarding your proposed construction.

You need to make your own mind up as to the safety aspects of the work. Last thing we want is for your health and safety to be in jeopardy.

On reading the thread containing the roof, where you said a ROR one is restricted because of room, have a look in the DIY Astronomer section, and look for a member called 'Centroid'

He converted his ROR Obs. to have a Turret, which was a great alternative to a dome. Could be worth some consideration for your own build.

Ron.

[Adamski]

Hello Sara, Having worked in construction for 20 yrs i can recommend maybe the use of a 2 pack epoxy resin specifally designed for fixing bolts into concrete. That way you can always re-drill holes in a different location without having to add more concrete. I have used such chemical fixers on many occasions and would trust my life with their stength. It' just another option if you are unsure.

[malc-c]

If you plan to build a brick construction then I would suggest you contact an Architect or as other have suggested a structural engineer. It would also be prudent to check if you need planning permission or equivalent given its above a part of the house (ok not attached, but you have a washroom / kitchen so there is chance that someone could be underneath all the additional weight. A typical brick weighs 2Kg ergo 200 bricks could weight almost half a tonne ! - and you'll be suprised just how may bricks you'll need for even a small wall, and then you have the weight of the pier, scope, and roof construction... it all adds up.

[Macavity]

In the semi-infinite number of TV programs re. self-builds in Spain etc., they always seem to be pouring TONS of reinforced concrete (flat roofing) - With impunity.

The usual question re. heat plumes and vibration seem pertinent? But, if I had the dosh (health?), I'd be sitting on a flat roof, somewhere warmer! Probably behind a bolt-on on METAL pier. I sense, if one doesn't "jump up and down" excessively, or live too near a major road...

[swag72]

Thanks for all your comments folks. All taken on board and asking questions etc as I type!

[Digz]

I would definitely seek help from an engineer on this one. Sorry, but in your other threads I didn't fully appreciate what you were planning to build your obsy onto otherwise I would have flagged this up earlier.

If this is traditional Spanish construction I would be wary with adding all that weight to it with a concrete base and masonry walls etc. The brick infill 'pots' are more than likely hollow and not very strong, relatively speaking. They would easily break with point loads on them. You should be looking to try and put all your loads back to the beams and columns - here is where an engineer can help as they can advise on whether there is sufficient capacity in the existing columns and beams etc.

If there is sufficient capacity in the beams and columns then a simple design can be developed which can utilise these (assuming they are in the right place for your obsy).

HTH