Which base would be best for vibrations?

[Astronut1982]

Hi guys,

I'm going to laying down the base for my roll off shed observatory in the next few weeks.

I am torn between laying slabs & cementing them down or just laying concrete 5" deep & putting the shed right on top of this. For the pier, I'll be using a 200mm diameter PVC pipe with rebar inside in a pit 3" x 2" x 2" all of which will be filled with postcrete to hold my NEQ6.

Can anyone let me know which of these would be best with regards to vibrations?

Thanks in advance,

Jeff

[Bizibilder]

The important thing is to isolate the pier base from the part of the base that you will be standing on otherwise vibrations from your walking about etc will transmit to the pier/mount. Personally I would go for concrete as it is cheap and absolutely solid - If you are moving a shed about on it you will not want it to settle or move as the weight moves about on it.

[Astronut1982]

Thanks Roger, thats what I though but I just wanted to check before I went ahead & ordered the materials.

Whats the best way to isolate the pier from the rest of the concrete as the pier will be in the centre of one half of the base, should I put in wood or some other material between the pier & the other rest in order to seperate the two & to dampen any vibrations?

Jeff

[Astronut1982]

Or would it be best to dig & fill in the pier 1st & then leave some soil around the pier when I dig out for the rest of the base? If I left some soil between the two that would surely help with vibration problems wouldn't it?

Jeff

[Gina]

Many people use polystyrene or polyurethane foam between the concrete base and the concrete floor.

In my obsy I used a wooden floor on beams and joists supported on 6 concrete pads well away from the pier base.

[Astronut1982]

How thick would the foam have to be Gina?

Jeff

[Astronut1982]

I think I'll need to go with the solid concrete base so it can support the runners for the roll off shed & also because I've just been paid off from my work so I need to keep the cost as low as possible.

Jeff

[Gina]

How thick would the foam have to be Gina?

Jeff

An inch or two is sufficient I believe but maybe someone with more knowledge of this method could advise you.

[Bizibilder]

I used the stuff builders merchants sell for filling expansion gaps in concrete (don't know its official name!). It is a "firm" foam strip about 150mm wide and sold im 10m lengths - it is about 1.5cm thick. Worked a treat put in double all round the pier block before pouring the base of my observatory. I left it in place and have had no problems with it.

[Astronut1982]

Thanks for the info Roger. I'll ask my Uncle what it's called, he's a sub contractor so he should know.

Jeff

[nytecam]

A roll off shed observatory = shift obsy as a whole to expose pier or roll-off-roof?