Copeland Park Observatory

[RikM]

We made a proper start on the obsy build today. It will be a standard 3m x 2m roll off roof design, self built rather than a shed conversion.

Following constructive advice on footings, I lifted the breeze blocks and dug in a double-height set at the front (down-slope) set on slablayer. There are only single blocks at the back due to the slope but these are dug in as well. They are all now nice and solid and I had a few blocks left over to make into steps. The floor frame is drying after the second coat of creocote. I will screw it all together properly tomorrow and put bits of DPM between the frame and the blocks.

 

I also dug the hole for the pier. I intended to go down 60cm, but hit a solid layer of broken brick rubble at 45cm, so will use that as the base instead of packing in hardcore. I will drive in a few 3ft lengths of angle iron to anchor the pier as well. I am going to use a 2.1m length of 160mm PVC waste pipe as the pier and intend to fill it with either sand or postcrete, haven't decided which yet but most probably postcrete.

I cut all the uprights for the wall frames, built the frames for the two end walls and covered one of them with 1200 gauge DPM before running out of staples. I also cut the shiplap for the end walls. While I was doing that, Nicki gave the rolling-rail supports and end wall shiplap a couple of coats of preserver. I forgot to take a picture as we packed it away in a hurry after imagining feeling a spot of rain. Sorry about the camera shake, this is a 4sec hand-held shot

Finally, I made a start on a set of garden Jenga from all the off-cuts

Just need to chuck a tarp over the floor frame and I'm done for today.

[Beulah]

Made a great start there. Just love the privacy of your garden.  

[laser_jock99]

Tangible progress there- keep us posted.

[RikM]

Okay, a couple of questions today.

Do I wrap the DPM around/between the frames (as diagram) or cut it square to the outside faces of the frames only, so they fit together wood-to-wood?

Should I use proper concrete to fix the pier or will a dozen bags of Postcrete do it?

Do I need to fill the pier tube with concrete/postcrete as well?

[callump]

Hi Rik,

I think I would not wrap the dpm round the frame at the bottom - it could trap water / condensation that runs down leading to rot.

I would say to use plain concrete mix (for foundation and pier) - I'm not sure postcrete is very good for large volumes - i'd be worried about the bottom setting properly. And you don't want to do it in layers.

Callum

[RikM]

My last day off for a while Back to weekends only to work on the obs.

I got the floor frame all screwed together. I have decided that joist hangars are a pain in the rear, but then, I've no idea of the correct installation technique.

I did a dry fit of the floor panels both to get a feel for how flat/stable the frame is and to double check that it is square. The diagonals both measured 3603mm, so I was pretty confident. They are not cut to length yet, so no pics. I will need to lop the 20mm tongue off the end one as well.

I am a bit worried about getting a long enough dry spell to get the floor down, walls up and clad plus roof on in one day, so I pre-clad one end wall today, making sure it was all nice and square. I think I'm going to pre-clad the lot, like a kit form shed build.. I had 10 year old help with the nails as well Last day of half term for Matty. We used stainless 41mm ring shank nails for this. I'm going to bring a 3mm ejector pin from an injection mould tool home from work to use as a punch to knock them in sub-flush. I'm not paying £6 for a set when I only want one!

If I can get the floor down and walls up in the one day, I have a big enough tarp to throw over, but there's a chance I will get the roof done as well. I am planning on making up the roof frame in the same way as the walls, so it's a kit.

That's probably it until next weekend apart from 6x casters, 2x 5m ali-angle and a powered 7 port D-link USB 2.0 hub turning up at work during the week.

[RikM]

Wheels turned up today

I'm trying to watch the budget on this project. Would a few layers of 10mm bubble wrap be useful insulation for the warm room?

[Stargazer33]

Okay, a couple of questions today.

Do I wrap the DPM around/between the frames (as diagram) or cut it square to the outside faces of the frames only, so they fit together wood-to-wood?

Shouldn't the DPM go under the floor frame? I thought DPM was to stop damp rising up through brick/block work to joist levels.

[RikM]

Shouldn't the DPM go under the floor frame? I thought DPM was to stop damp rising up through brick/block work to joist levels.

I've put bits under the floor frame joists, a whole sheet between floor frame and floor boards, and then between the wall frames and the shiplap. 

[malc-c]

Looking good so far.

Regarding the DMP, if you have enough then it wouldn't hurt laying strips on the top of the joists / frame to form a barrier between the blocks and floor. 

Personally I would use 18mm external grade ply for the floor.  With the frame so near to the ground there could be a chance of dampness penetrating up and over time any form of particle board will deteriorate.  That said, 18mm chipboard (high density) is used in construction of mobile homes, so it can work, but then the floor on a mobile home is typically a couple of feet above a concrete base.  If you do opt for chipboard then lay the floor on the inside of the wall frames so you can at least lift it and replace it in the future should it need it.  Also doing it this way means you could put  your wall panels up, then sling a tarp over the top and then lay the floor...

[RikM]

Looking good so far.

Regarding the DMP, if you have enough then it wouldn't hurt laying strips on the top of the joists / frame to form a barrier between the blocks and floor. 

Personally I would use 18mm external grade ply for the floor.  With the frame so near to the ground there could be a chance of dampness penetrating up and over time any form of particle board will deteriorate.  That said, 18mm chipboard (high density) is used in construction of mobile homes, so it can work, but then the floor on a mobile home is typically a couple of feet above a concrete base.  If you do opt for chipboard then lay the floor on the inside of the wall frames so you can at least lift it and replace it in the future should it need it.  Also doing it this way means you could put  your wall panels up, then sling a tarp over the top and then lay the floor...

Unfortunately, I already have the 22mm high density chipboard T&G floor panels (on the recommendation of the timber company). I will try and work out how to mount it inside the wall panels. At the moment I can't because the floor joists are only 47mm wide and the wall panels are 75mm due to the lengths being layed down rather than upright.

I don't anticipate staying in this location longer than about 5 years, so I may just lay the chipboard floor in the normal way and look after it carefully. I bought enough DPM to go between floor frame and chipboard floor panels. I got 4x15m so can lay it in a single panel rather than strips. (again, on advice from Nick's Timber in Glos, who have a very good reputation as a supplier).

[malc-c]

I'm trying to watch the budget on this project. Would a few layers of 10mm bubble wrap be useful insulation for the warm room?

I personally don't think you will notice much difference from the outside... novel idea though.

• Kingspan - excelling foil backed insulation - but expensive
• Jablite premium - very good insulation board, cheaper than Kingspan
• jablite Universal - again good insulation board, and 1/4 the cost of premium, but with a lower
• Styrene - less dense than the above - but cheap

All the above will insulate the warm room well - with 50mm between the joists and 25mm minimum in the walls and roof.

• Rockwool - cheaper, but needs a vapour barrier to prevent dampness - also a pain to install !

[RikM]

Lots of work done today but not much visible progress. I built the frames for the two long walls. The garden is still sodden so I had to build the first one on the patio, which seems made to measure for the job. By happy coincidence the wood patio framing came from the same place as the obsy wood and being a lazy efficient chap, I had decided not to cut it down, so it is exactly 3m across

With a bit help from my eldest, I sat the boards on the floor frame and used that to build the last wall frame. I remembered to leave a gap for a door in this one. I left the camera sat on the table, so my wife decided to take this shot of a fat bloke in a hat

I don't have any more pics from today but I wrapped the long wall frames with DPM. Put little strips of DPM between the foundation blocks and the frame and hammered in 4x 1m lengths of angle iron as ground anchors, to which I have screwed the floor frame. That really did me in for today! Nicki painted another dozen or so lengths of shiplap. My last job for today was to cut the little short lengths of shiplap to go on the blind-side of the door (don't know what else to call it).

I have a feeling this build thread is going to look like nothing is happening for ages because all the bits are stored in the garage. Once everything is ready and we get a nice weekend I should be able to just assemble the thing in one go. I hope.

[Beulah]

Do keep posting if you have the time Rik, I do enjoy build threads. 

[Mike73]

I have a feeling this build thread is going to look like nothing is happening for ages because all the bits are stored in the garage. Once everything is ready and we get a nice weekend I should be able to just assemble the thing in one go. I hope.

Forecast is looking good for the weekend, Copeland Park Observatory should be up and running by Sunday pm then?

[RikM]

Hopefully it will have walls and a roof on by Sunday. Whether the roof will open? Fingers crossed

[Mike73]

I've just scrapped my plans for an obsy  . Going to make a dedicated scope storage shed instead, quite looking forward to building it now. 

Anyway, goog luck with the build Rik, I'm watching with interest.

[Beulah]

Mike, make sure those shed doors are wide - you need room for manoeuver when carting those scopes around!

I like the observatory someone posted on here once (can't find the link ATM) - an obs that could be literally opened on a hinge and split in half - looked ideal for dobservers like us.

[RikM]

Good day today

DPM over the floor frame, then T&G chipboard panels down.

I left a trap door for the pier tube to drop through once I know what height to make it.

Wall frames screwed in place and joined with heavy duty angle brackets in the corners as well as monster screws.

Lola has already decided it's a big dog house So we have put her spare bed in the warmroom.

Not much room round the back for installing shiplap!

Tarp over the top until tomorrow. Turns out I can't find our straps for it so I've tied bags of gravel to it with coax cable as an emergency measure

Night night Obsy

[dmahon]

Not sure about the DPM under the shiplap. I'd have used vapour barrier, but a bit late to mention it now. I guess if there are any condensation problems you can always make some holes in it

[MikeP]

I've used thick gauge polythene under shiplap a few times when building sheds (moved house quite often) and its never been a problem.  I'd be slightly more nervous about the chipboard on top of DPC on the floor but it is probably OK.

Mike

[malc-c]

To be honest other than the DMP in the brick course I didn't use any vapour barrier under the shiplap or floor and never had a problem with condensation on the walls etc.  I did experience an issue this year with condensation forming on one of the internal cupboards which over time started to run down the side of the panel and make the carpet tile wet, but this was due to the observatory being shut up for months on end.  

[RikM]

I am hoping the DPM will keep most of the moisture outside and a dehumidifier will take care of the inside.

[RikM]

Too busy for proper photos today

All the shiplap on the walls is on bar the top and bottom courses. I need to cut the bottom course down by 40mm but simply ran out of time on the top one. The rail supports and rails on the main obsy are on but the outboard rails and posts are only temporarily propped up rather than fixed in place. I'm going to use bolt down post holders for the ends of the runners rather than dug in posts to give a bit more wiggle room. The roof frame is done. Seen here upside down because I had just fixed the wheels in place.

We demounted it, flipped it over and fitted the trusses, then fixed the rails (50x25x3mm aluminium angle) and dropped the finished roof frame on top. Having done that, it turns out that it had twisted out of square while fixing the trusses  It's only a dozen screws for now, so tomorrow I'll undo them, square it up and re-fix it. I will leave it on the runners for that to make sure it fits properly. It actually rolls now, even though it is out by about an inch on the long side.

If I can leave work on time this coming week, I can get an hour per night in so there should be some good progress.

[RikM]

Day off today to take advantage of the dry day.

Started by getting the roof boards on. Quite scary being sat on a roof of my own construction. It seems quite high from up there. 

Rollers roll nicely

Nicki helped by painting more shiplap and also built the door for me

Didn't quite get the outboard rails done today. My little Black & Decker isn't really up to putting 14mm holes in concrete blocks. I had to take it steady so as not to overheat and fry it.

Made a right pigs ear of the felt. Bitumin adhesive is nasty and I miscounted which nail to paint up to, so I have a lovely skunk stripe down one side of my roof. I have also ended up with it looking a bit wrinkly. Note quite sure why, I went over it with a roller when putting it down. Could be something to do with having a fat bloke sat on it during installation, anyway, nothing I can do about it now. There is a 30cm overlap and the entire roof is bitumined underneath.

No pictures but I have sliding bolts to hold the closed end down and 6" hasp and staple latches for the rolling end.