Construction 1

Barking Dog Observatory

Sliding Split-Roof Observatory

First thing, get the site right. Make sure you can see Polaris, and that you have a reasonably unobstructed view to the South and hence of the ecliptic. The site I chose was pretty much dictated by the garden lay-out and so as not to overlook neighbours. Fortunately I have a good view of Polaris and now, after extending the rails on which the roof slides, a good view to the South. The type of construction I chose was mainly on economic grounds but also, in my case, a split roof affords some shelter from the North winds and from light pollution. It has proved to be both sturdy and practical but even now almost two years after first light I continue to make modifications!

Here is the original recipe (a la Delia):-

Ingredients:-

One 8'x6' sturdily built ship-lap shed, with wooden floor.

2"x1" treated batten in 8' lengths x 20 (approx)

2"x2" treated timber in 8' lengths x 10 (approx)

4"x1" treated timber in 8' lengths x 6 (approx)

Ship-lap to match the shed construction (as required)

3"x3"x6' treated fence posts and metal spikes x 4

PVC pond liner (instead of using roofing felt)

1"x½"x6' wooden strips (or 8') (as required)

1"x1"x6' plastic angle strips (or 8') (as required)

Foundation blocks x 16 at least

Concrete sufficient to bed a pier or form a slab for a tripod to stand on.

Screws ¾"No6, 1"No6, 1½"No8, 1¾No8" 2½No8" 3"No10 (as required) Use screws for all fastenings, including shed erection.

2" angle brackets (as required)

4x strap hinges 4" or 6"

Extra strap hinges for door, preferably with coach bolts for attaching.

Plywood for reinforcing door fastenings and mounting electrical equipment.

Cabin hooks, long roofing hooks, various springs and lots of other useful things that escape me at the moment.

Oh yes, time, helpful children and a patient wife!

And here the making:-

1) Cut a hole in the centre of the floor big enough for a pier to pass through or for a concrete slab. I laid a concrete slab about one third of a metre in thickness by one metre square (big enough for a tripod, extended to a convenient height, to stand on). Initially I used the telescope on its tripod but I quickly made a pier for the mount to stand on (see photo 1 on shed photo page).

2) Place and level the foundation blocks around the slab or pier foundation so that they will support the remaining floor joists. If you have formed a slab make sure that the blocks are below the level of the slab top so that when the shed floor is laid it is at the same level as the slab top.

3) Saw each end piece of the shed to the same height as the sides, keep the gable ends as these will form the ends of the sliding roof sections. The height of the door will have to be lowered. Reinforce each of the shed end pieces and each of the sawn off gables with batten (see photo 2 on shed photo page). Fit, but do not fasten, extra ship-lap to the bottom of each gable end so that it will form a small overlap (about 1") over each shed end. You will need to trim the ends of these pieces later to allow the roof to run on the rails (see photo 3 on shed photo page).

4) Take each of the two roofing panels, measure them and saw exactly and squarely in half. Make an ID mark on each sawn panel so that it can be placed alongside the piece from which it was sawn.

5) Cut 4"x1" timber to fit under the bottom edge of each roof panel (ie 4' long approx) so that when the roof is assembled the 4"x1" will be on the inside of the roof and will form the slides. Cut a square approximately 2"x2" out of one end of each length so that it will be positioned where the gable end frame will be attached to the roof panel (see photo 4 on shed photo page).

6) Check that these lengths fit on the inside bottom edge of each roof panel, trim to fit if necessary and then fasten them onto the inside bottom edge of each roof panel so that the cut outs face the ridge of the roof (see photo 4 on shed photo page).

7) Along the sawn edges of each roof panel, fasten a length of batten on the inside edge between the runner and ridge timber (see photo 5 on shed photo page).

8) Cut two pieces of 2"x2" about 10" long. Saw the ends of these at the same angle as the gable ends so that they can be used as ties in the ridge of the roof (see photo 5 on shed photo page).

9) Now attach one of the roofing panels from one end of the shed to its gable end. You can use the other gable end as a temporary support. Attach the other panel and use one of the pre-prepared roof ties to fasten the free panel ends together.

10) Turn the roof structure onto the gable end. Fasten a temporary batten, about half way, across the end to which you have attached the roof tie so that the roof panels are squared up.

Continued on Construction 2.

These notes are for guidance only and may contain inaccuracies.