Shed on existing deck

[Fortwilliam]

Hi guys. I laid down a deck almost 12 years ago, now I plan to erect a shed on part of it measuring 7' 6" x 7" 6". The deck boards have grooves on top. The deck is solid as a rock, I will have a telescope in the shed so need to keep the floor firm. What is best to use for the flooring?

I don't have any problems with drainage from the deck but am still concerned with rain getting into the flooring of the shed. I intend to have an overhang on the roof of 3" but rain will get into the grooves. Should I put a DPC between the floor and the deck?

Regards from Ireland,

Ed.

 

[Paul.J]

Don't you mean you are putting a wood lathe in the shed :?:

EDIT-: This was originaly posted in the woodturning section hence my reply.

 

[defsdoor]

I'd raised it off the deck. Water will stay under the shed despite any gradient as the grooves aren't big enough if covered (the water will stick).

 

[Brianp]

I would be a little wary of a deck as a foundation for a telescope - I did some long exposures of the night sky from my own deck recently and there was some entertaining but not altogether accurate bouncing showing up in the picturegrams. What seems rock steady, might not be. That's not to cast aspersions on your deck or your judgement of it, just some experience I've had here. I would raise the floor off the deck a little too, make sure that you don't get the floor of your shed sitting in any ponded water. Chances are once you've put it up, the channels in the deck might get blocked a little more often.

 

[RogerS]

Ed You might like to contact this guy as he has a dedicated shed for his telescopes and is a very keen and knowledgable amateur astronomer.

http://www.baddileysuniverse.net/AstroKit2.aspx He has a Contact Me button. I suspect he used a concrete base.

Or look at this

http://www.skyatnightmagazine.com/featu ... scope-pier

 

[Spindle]

Hi

The most rigid mounting you will get is to mount the telescope directly to the deck or to risers hard mounted to the deck - any interim floor will introduce relative movement. But as indicated by Brianp, decking, no matter how rigid it feels, will be unlikely to be suitable for astronomical observation / photography.

Regards Mick

 

[Fortwilliam]

Hi all, thanks for the replies. Apologies for the wrong forum, I clicked a link after reading a post.

My telescope is a 10" goto Dobsonian, the circular base is about 20" in dia, and does not sit on a tripod or pier. It's a bit of a beast to move up 7 steps to the deck, hence the new shed.

You've got me thinking though - I've seen other sheds with piers for scopes but the pier for this Dob would need to be at least 20" dia! That would mean cutting through at least one of my deck joists and digging a VERY large hole and another two to support the cut joist. But, as my friend says, you are better looking at it than for it. It would be a horrendous job to do with a shed in place. Back to designing. (hammer)

I need some advice though on the flooring - OSB or ply? How thick?

How far to raise the shed off the deck? Or could I maybe seal the channels around the base to prevent water getting under it?

I've been using the deck since it was built with a 6" scope and have taken some cracker pictures of the moon, fast -ish speed, using a remote on the camera. For everyday, night!, viewing for myself and the grandchildren it has been fine. Living in the city I would not expect to get decent long exposure photographs anyway.

The more I think about it - the more I want a pier!!

Ed.

 

[Paul.J]

Hi Ed and welcome
Could you not cut a hole in the floor and lay slabs on top of each other,2'x2's should be ok,upto the level of the shed floor??

 

[Fortwilliam]

Hi Ed and welcome
Could you not cut a hole in the floor and lay slabs on top of each other,2'x2's should be ok,upto the level of the shed floor??

I like it! The deck joists are 16" on centre giving 14" gaps. So if I build up between the joists using 2' x 14" slabs and place a 2' x 2' slab on top, not touching the deck, there would be 5" overhangs on two sides. Is this too much?

 

[John Brown]

An old snooker table sitting on partially inflated lorry inner-tubes provides a fairly stable platform, or so my old book on making your own holograms tells me.

 

[Fortwilliam]

An old snooker table sitting on partially inflated lorry inner-tubes provides a fairly stable platform, or so my old book on making your own holograms tells me.

I have an old snooker table! Now to find some inner tubes. LOL.

 

[Fortwilliam]

"I need some advice though on the flooring - OSB or ply? How thick? "

Any advice would be most welcome.

 

[Spindle]

Hi

If you are going to mount the telescope directly to the concrete slab pier then the floor needs only to support you and any other equipment in the shed - I guess 19mm OSB would be fine as long as the shed remains dry. Make sure that the floor does not contact the pier or it will transmit vibration to the telescope.

Regards Mick

 

[Paul.J]

Ed- I've used 18mm shutter ply on the floor in my shed which has been down for about seven years now and still shows no sign of wear, its used everyday in and out the shed to the garage/shop in all weathers.
Not sure if OSB will be too soft for walking on??
As Mick says keep a sufficent gap between the floor and the pillar.

 

[carlb40]

If you have something solid under the decking? Why not just build 2 pillars from concrete blocks either side of your joists. Then bolt some steel tubing to the blocks and a steel plate to the tubing to provide a base for the telescope.

 

[Fortwilliam]

If you have something solid under the decking? Why not just build 2 pillars from concrete blocks either side of your joists. Then bolt some steel tubing to the blocks and a steel plate to the tubing to provide a base for the telescope.

I can do that for my smaller scope using the mount off its tripod. I can do something similar for the Dob - just have it sitting on a slab.

Now for the next problem - I'm going to roll off 1/2 the roof, I'm thinking of using 2 pieces of aluminium to keep rain out of the split. One straight piece screwed onto the edge of the non-moving part of the split roof and sitting proud of it by 1/2 an inch. The other piece a channel used upside down and centred over the top of the straight piece when the roof is closed. How do I stop insects from getting into the shed through the split?

 

[Spindle]

How do I stop insects from getting into the shed through the split?

Hi

How about using a brush type draught excluder?

Regards Mick

 

[Fortwilliam]

How do I stop insects from getting into the shed through the split?

Hi

How about using a brush type draught excluder?

Regards Mick

That'll do the job, thanks Mick.

 

[Benchwayze]

A telescope needs to be attached to terra firma. Especially if you are going to indulge in astro-photography. The more massive the bearings and column the better. On a wooden deck, however firm it seems, you could experience 'shake'. Any slight shake will be magnified by the eyepiece you are using; the higher the power naturally the more the shake will be noticed.

Hope that helps; and that you don't have any street-lights too nearby!