Astrokev's ROR - The Build

[Gina]

I used shiplap on mine.  Still fine after several years but could do with a coat of wood preserver now I think.

[Astrokev]

My concern with what I've seen so far is that cladding is prone to warping and may not lay flat against the studding frame. For the price you pay for this stuff you expect it to be fit for purpose. Not sure what you can do about this as its part of the drying process I guess. More expensive timber is an option I suppose, but this is really outside my budget.

I noticed  the other day that the tongue and groove timber used on my "cabin"  has also warped badly in the recent heat and there's now a sizeable gap between a few of the timbers. This has been up for 5 years without previous problem. 

Any thoughts on how this can be minimised or is it just a risk one has to take?

[Yawning Angel]

The step up from there seems to be loglap, which is T&G rather than overlapped, but another notch up in price. It gives a 'cabin in the woods' look, and tends to hold it's shape, due to the curved cross-section

[JamesF]

My experience is that feather-edge boards are not as well seasoned and more prone to warping than shiplap.  I can only get them in shorter lengths, too, which can mean there's more waste and more joins where the elements can get behind the boards.  I used shiplap for the treehouse I built for the children and that has survived pretty well.  I nailed it to every upright in the walls with two nails per upright.  It has shrunk a little, but not enough to expose gaps.

James

[Davey-T]

Timber will shrink ( and grow ) according to the weather, if you use too many fixings so that it can't move it will simply split along the grain also any knots will continue to bleed for a couple of years if in direct sunlight.

You could try giving the inside surfaces a coat of finish the same as the exterior as it may help stop curling up.

You could use PVC cladding, even more expensive, but need no maintenance only a wash now and then.

You could cover the whole thing in OSB and paint it.

Dave 

[Gina]

I thought of PVC cladding which I had used on a new back porch for the house but the cost for all 4 walls of a 5m x 2.5m x 2m (more in places) structure was prohibitive.  Also, at that time I could only find it in white which would have made the observatory stand out like a sore thumb in the green environment!  Good quality redwood shiplap for the local timber merchant, though costing more than standard shiplap, was very much cheaper than PVC.  After several years the redwood shiplap is fine.  And yes, I did coat it both sides with good quality wood preserver.  IMO it paid to go for the best in timber option.

[Astrokev]

Thanks for the replies everyone - very helpful.

So far I've compared a mainstream supplier, Jewson, with a local timber merchant.

Jewson only seem to supply 19x125 (finished size around 15x120). Baffles me why they bother to quote the unfinished size as this is of no use to man nor beast as far as I can see!

Local timber merchant has 25x150 (unfinished size. Actual thickness is nearer 19) which is better I think. I'd prefer something a bit thicker than the Jewson stuff, which seems too flimsy to me.

PVC is an option as suggested, but my personal preference is to stick with timber.

[Macavity]

I sense the colour does make quite a difference. For aesthetics, I paint most
things (observatory, fences etc.) Dark Brown... And they all warp quite a bit?
The observatory is like a "greenhouse" these days! Thinking of cladding the
sun-side with something that is rather less absorptive / more reflective? ?

Edited July 6, 2018 by Macavity

[Davey-T]

24 minutes ago, Astrokev said:

Baffles me why they bother to quote the unfinished size as this is of no use to man nor beast as far as I can see!

Cause that's the size of timber they charge you for 

Dave

[Dr_Ju_ju]

I won't ever frequent Jewson again after they tried to charge 3 times the Wickes price, for 75x75 fence post, it wasn't even tanalised. Jewson really only want to deal with tradesmen who can offset the higher prices to their clients.

Wickes isn't always the best quality, but if you have the time to search through the store items, you usually get what your after....

[RayD]

55 minutes ago, Astrokev said:

Thanks for the replies everyone - very helpful.

So far I've compared a mainstream supplier, Jewson, with a local timber merchant.

Jewson only seem to supply 19x125 (finished size around 15x120). Baffles me why they bother to quote the unfinished size as this is of no use to man nor beast as far as I can see!

Local timber merchant has 25x150 (unfinished size. Actual thickness is nearer 19) which is better I think. I'd prefer something a bit thicker than the Jewson stuff, which seems too flimsy to me.

PVC is an option as suggested, but my personal preference is to stick with timber.

I hunted high and low, Kev, and ended up finding a company (proper timber merchants) selling through eBay and the quality and cost was exceptional. Not one bad section, available in a variety of lengths so you only order what you need, and delivered to the door. I'll have a look and dig out the details but well worth a look if you not ordered yet. 

[Astrokev]

15 minutes ago, RayD said:

I hunted high and low, Kev, and ended up finding a company (proper timber merchants) selling through eBay and the quality and cost was exceptional. Not one bad section, available in a variety of lengths so you only order what you need, and delivered to the door. I'll have a look and dig out the details but well worth a look if you not ordered yet. 

That sounds like the holy grail there Ray!

Yes, if you have any details, that would be great ? 

[Astrokev]

1 hour ago, Macavity said:

I sense the colour does make quite a difference. For aesthetics, I paint most
things (observatory, fences etc.) Dark Brown... And they all warp quite a bit?
The observatory is like a "greenhouse" these days! Thinking of cladding the
sun-side with something that is rather less absorptive / more reflective? ?

My current plan is to paint with preservative and then paint with a pale colour to match the cabin to try and reflect the heat as much as possible.

[Gina]

If you provide adequate ventilation a wooden observatory won't get as hot.  Even in this very hot weather in full very strong sunshine my observatory has been quite acceptable to work in.  And I can't stand much heat.

[RayD]

4 hours ago, Astrokev said:

That sounds like the holy grail there Ray!

Yes, if you have any details, that would be great ? 

These were the people I used, Kev. Really good wood, quick delivery and if you measure up well you can order lengths that minimise cuts so saves quite a bit of waste. 

[Astrokev]

25 minutes ago, RayD said:

These were the people I used, Kev. Really good wood, quick delivery and if you measure up well you can order lengths that minimise cuts so saves quite a bit of waste. 

Thanks very much Ray. I'll check them out ?

[Astrokev]

Hmm ?.

Starting to make the catchment structure on the gable ends. It seems that I've gotten a few measurements wrong somewhere along the way and the gap between the track-rails and the timber that will form the capture rails is too big. Not sure how that happened. I could probably make do and fudge it, but that's not my way and it would only bug me. If I moved the capture structure in to where I want it, this would leave the roof beams sticking out by a few centimetres, which would look unsightly and expose them to the elements. My design is to have the ends of the beams covered by the cladding on the gable ends, which will give them more protection.

So, have decided to remove the rafters at the gable ends, trim the ridge and N & S beams back by around 17mm, and then re-attach the rafters. A lot of faffing to do this, but I'll be happier when it's done and, well, I guess I've got the time....

[nightvision]

It can be quite alarming seeing seasonal daylight appear between cladding boards or via knot holes! 

You could take the cladding purchase off the critical path; separate aesthetics from structure and get your obsy operational by sealing the whole structure in 9mm exterior shutter-ply (only £14.40 for 2440x1220 sheets).  More stable than ship-lap or feather-edge cladding and more resilient than OSB.  Leave a few mm expansion gap between boards and seal with silicone.

For about £150 it would give you a weather and bug proof structure in one day,   

At a later date you could install any cladding on top of the ply (make sure to mark the stud locations).   It won't matter what warps or shrinkage you get in the cladding you choose as the box will already be sealed.

[Astrokev]

1 hour ago, nightvision said:

It can be quite alarming seeing seasonal daylight appear between cladding boards or via knot holes! 

You could take the cladding purchase off the critical path; separate aesthetics from structure and get your obsy operational by sealing the whole structure in 9mm exterior shutter-ply (only £14.40 for 2440x1220 sheets).  More stable than ship-lap or feather-edge cladding and more resilient than OSB.  Leave a few mm expansion gap between boards and seal with silicone.

For about £150 it would give you a weather and bug proof structure in one day,   

At a later date you could install any cladding on top of the ply (make sure to mark the stud locations).   It won't matter what warps or shrinkage you get in the cladding you choose as the box will already be sealed.

Hmm, that gives me something to think about ?. Thanks Tony for the suggestion. Certainly like the idea of sealing the walls prior to cladding to remove impact of shrinkage leaving gaps between the boards. It would also make the walls more secure. Must think on that.

Edited July 7, 2018 by Astrokev

[yesyes]

I put plastic foil under the cladding for that reason. Ply is of course a better but more expensive way.

[Astrokev]

OK, so off came the rafters and noggins, ridge beam and N & S beams cut back by 17mm, rafters and noggins put back on. I'm now back to where I was at 9.00 this morning - except that the capture structure should be a much better fit ? .

Following the suggestion by @nightvision I'm now pondering on whether to skin the obsy in ply or OSB before I put on the cladding. Much as though I'd like to get the OSB and EPDM on the rolling roof, it will probably be easier if I can clad the gable ends first, so this is now top of the priority list....

 

[nightvision]

This loglap seems good value and is unlikely to come apart like shiplap.  

Loglap at £1.30 a metre: https://www.ebay.co.uk/itm/100mm-x-22mm-TREATED-SHED-TIMBER-CLADDING-LOG-LAP-GRADE-A-SEE-POSTCODES-/272755487107?_trksid=p2385738.m4383.l4275.c10&var=571890564978

 

[Davey-T]

12 hours ago, Astrokev said:

So, have decided to remove the rafters at the gable ends, trim the ridge and N & S beams back by around 17mm, and then re-attach the rafters. A lot of faffing to do this, but I'll be happier when it's done and, well, I guess I've got the time....

Times like this you're glad you didn't use a nail gun 

Dave

[Astrokev]

Not much progress on the build today. For one thing I was at a family BBQ enjoying some social time. The other reason was it was just too hot. Electronic temp sensor was reading 33.9'C in the shade this afternoon, and it felt it! Phew!

This evening I did manage an hour though. I stuck down the edges of the EPDM to the side of the track rail with contact adhesive. I can now trim this which will enable me to make the catchment structure and check for clearance along the entire length of roof travel.

The other big news is that I've now decided to put an OSB skin on the outside walls and then put cladding on top of this. This will make the building much more secure and will remove any risk of gaps caused by shrinkage of the cladding. The downside is I'm going to have to remove the breathable membrane I'd already put up, as this needs to go on the outside of the OSB. Started this this evening; a slow job trying to remove the clout nails without damaging the membrane, but well worth it.

 

[Astrokev]

So, I've now realised my first major design flaw of the build..... I say major as I'm sure I've made loads of minor ones!

I originally didn't intend to put sheet material on the outside of the walls, just cladding. Therefore, I intentionally designed the wall studding to be less than the more conventional 400mm centres to give it more strength. This is fine except that the studs now don't fall conveniently to allow me to use full sheets, without adding more stud work. I'll have to cut the sheets to suit, which will be more wasteful and time consuming. Oh well, lets hope this is the only significant design flaw!

The other thing I would have done differently is to inset the wall studding from the edges of the floor to allow room for the OSB sheets. This isn't a major problem, I just would have done it differently had I considered this approach when I designed the obsy! Onwards and upwards ?