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Subfloor over concrete pad for dome?

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#1 kiwiguy

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Posted 08 January 2020 - 03:34 PM

I've seen the advice about having a concrete pad only the same size as your dome to prevent water issues.

I have a 10x12 pad, and am about to assemble my 8 foot NexDome.

I'm wondering how much I need to plan around water issues.  I live in Northern Californa, no snow, but winter can be wet.

 

Initial plan is just place dome on concrete, secure to pad and seal around perimeter with caulk.  Pad was designed with a slight slope.

 

I've used the DriCore subfloor in a basement before, which are 2x2 plywood panels with a grooved plastic underlay for water and air flow.

I could install these first over the concrete, then put the dome on top, and trim the edges.

Or I could install these in the future, but would be inside the dome.

 

How about just epoxying the floor like with a garage?

 

The intended operation is all remote so I plan not to spend much time in the dome.

 

Any advice or experience would be greatly appreciated.

 

Thanks!



#2 TMO

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Posted 08 January 2020 - 03:59 PM

I have a 10-foot diameter concrete pad for my 8-foot NexDome in Northern California's Sonoma County, similar to your climate.  I caulked around the perimeter of the NexDome, so water doesn't seep into the dome.  It works.  No water gets into the dome from the perimeter, nor from the NexDome itself.  I put electrical conduit under the pad (before laying the concrete) to bring in 120VAC and USB lines to the telescope.  Some photos are here:  http://taylor-mounta...y-construction/

Good luck and Clear Skies! 


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#3 TeslaTrek

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Posted 08 January 2020 - 04:40 PM

Alternatively, you might consider building a stem wall around the perimeter of the observatory.  Make it at least one step up off the ground.  I covered the interior ground with thick plastic with gravel under and over it to reduce moisture.  Installed joists over the stem wall; this makes for a comfortable floor to walk and stand on.



#4 Simcal

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Posted 08 January 2020 - 04:40 PM

Beware, garage type floor epoxy will eventually degrade and peel due to UV, so only good for inside / shaded.  



#5 Simcal

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Posted 08 January 2020 - 04:51 PM

If you think you're going to have a lot of rain / runoff coursing over your pad, then you could try to use something like this to build/frame a round raised deck.  This would then allow you to flash properly over the interface.   I guess this might provide further benefit in isolating the pier from the floor/dome.

 

https://www.ribaprod...PedestalSystem 

 

I've used the dimpled flooring in my basement, but it's only about 1/2" rise and didn't prevent a minor (sump pump failed) flood OVER the flooring.  When it got wet, of course the ply started to warp up on the edges causing a tripping hazard.  It did allow me to setup fans to dry out the underfloor after it drained.  But, it's only good for really minor dampness issues.

 

edit: added:

 

The stem wall is a good idea and could be as simple as a formed concrete wall poured on top of the pad. Drill some anchors into the pad to strengthen it (the wall interface to the pad) before the pour.  This is how we built a 'crib' for our hot tub.  Worked great. ( and zero maintenance ).


Edited by Simcal, 08 January 2020 - 04:57 PM.


#6 macdonjh

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Posted 08 January 2020 - 11:33 PM

I've used the DriCore subfloor in a basement before, 

Thanks, I need something like this for my observatory.



#7 rimcrazy

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Posted 09 January 2020 - 11:19 AM

My observatory is a building built over a large concrete pier.  Here you can see the base foundation being put in.

 

IMG_0439.jpg

 

Here is a shot of the finished floor showing the pier coming up from below:

 

IMG_1355.jpg

 

I changed the design mid way through construction so I increased the size/weight of the base pier:

 

Before:

IMG_1374.jpg

 

After:

IMG_1375.jpg

 

Pier bolted into the floor:

IMG_1567.jpg

 

Finished Building:

IMG_1673.jpg


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#8 Foundationer

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Posted 15 January 2020 - 03:20 PM

I build my nexdome first, (on a wooden deck). Then inside the building I installed a vapor barrier that was larger than the inside dimensions. I then installed dri-core flooring on top of that and trimmed off the excess barrier essentially creating a tub with about 1 inch high walls inside the nexdome. I've since seen some very heavy rain and my floor is clean and dry!

#9 piaras

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Posted 15 January 2020 - 08:18 PM

I used DriCore panels. I did not put vapor barrier on my wood deck, as this will cause rot on the top surfaces of the wood due to reduced airflow. The eggcrate underside of the Dricore allows airflow around the wood decking. I cut the panels to fit snug but not tight to the dome base and placed indoor/outdoor carpet cut to fit over top of the panels.

Pierre



#10 Foundationer

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Posted 16 January 2020 - 08:55 AM

My deck is treated wood graded for ground contact and also coated with spar varnish so I'm pretty sure rot won't be a problem. And even if it does, I'll be long dead by then😉

Edited by Foundationer, 16 January 2020 - 08:55 AM.


#11 kiwiguy

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Posted 20 January 2020 - 11:32 PM

I have a 10-foot diameter concrete pad for my 8-foot NexDome in Northern California's Sonoma County, similar to your climate.  I caulked around the perimeter of the NexDome, so water doesn't seep into the dome.  It works.  No water gets into the dome from the perimeter, nor from the NexDome itself.  I put electrical conduit under the pad (before laying the concrete) to bring in 120VAC and USB lines to the telescope.  Some photos are here:  http://taylor-mounta...y-construction/

Good luck and Clear Skies! 

I really like the way you raised the dome on a retaining wall.  I think I want to do something similar.  What type of wall blocks did you use?  I'm guessing they are 6 inches high.  Thanks!



#12 Celestialoptics

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Posted 12 October 2020 - 03:50 PM

I have a 10-foot diameter concrete pad for my 8-foot NexDome in Northern California's Sonoma County, similar to your climate.  I caulked around the perimeter of the NexDome, so water doesn't seep into the dome.  It works.  No water gets into the dome from the perimeter, nor from the NexDome itself.  I put electrical conduit under the pad (before laying the concrete) to bring in 120VAC and USB lines to the telescope.  Some photos are here:  http://taylor-mounta...y-construction/

Good luck and Clear Skies! 

Did you use a silicone based caulking? Do you know what brand/type? 




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