Period greenhouse & thanks

[Pford75]

Firstly, thanks to fellow PPUK'rs Flyfisher and Penners who visited me yesterday. They both offered some very welcome advice on some greenhouse repairs I will soon be undertaking. Thanks gentlemen.

One of the points we discussed was the choice of timber. AIUI, cedar is the traditional choice for greenhouse construction (largely because of it's thermal properties). However, I am really looking for something which will not require treatment and will survive a long time exposed to the weather. Oak is being considered, but am wary about movement which could be problematic in a greenhouse.

Anyone else care to comment on hardwood vs. softwood and choice of timber?

 

[middi]

Having owned 5 different sizes and different materials constructed " domestic" greenhouses ,for the purpose of orchid growing, I had the opportunity to evaluate how different materials compared from a performance and maintenance point of view. ( also helped my father maintain his commercial glasshouses in the 60's)

First and foremost, the decision to be made is the primary role the " repaired " greenhose has to serve in the overall scheme of it's confines. Ie-
1) Aesthetic appearance
2) crop growing
3) extra living space
4) overwintering tender plants
5) will it require heat
6) the existing construction materials
7) the time available to keep up maintenance
8) a mixture of the above
9) ( the storage of unused bikes and old lawnmoers under an overhanging tree in an obscure corner of the garden :wink: )

If ( as the case appears to be) the repairs need to be carried out on an existing " wooden" structure and the choise of repair materials has to be wood, what is the existing construction wood and does it require painting. If the replacement wood " components " can be left " open" to the elements and just " oil" treated then a resistant to rot wood will be more suitable. Unless the existing greenhouse has to be repaired in oak due to conservation or existing materials restrictions I would avoid the use of oak as this material, albeit extremely durable, is not a good choise especially for single glazed thin glazed bars. It performs much better when used in conjunction with toughened DG glass units due to the strength of these units aiding in the stability of the oak and it's characteristic distortional tendency.
This material is best used for base or sole plates or well " mastic bedded" DG units.
Whilst there are some examples of oak greenhoses the majority of " glass houses" ,at the height of theit popularity, would have been constructed from straight grained softwoods ( pines) and douglas fir being a very good choise due to it's strength and resistance to rot. This wood, coupled with the lead and arsenic based paints of the day, made a formidable long lasting greenhouse wood. Whilst the discerning and " rich" establishments could use Teak as a greenhouse building material ( the best choise of all materials) the commercial grower and home grower was restricted to softwoods and " poisonous" paints. Nowdays the choise for home greenhouses is invariably cedar, if wood is preferred, or bare alumiuium with choises of anodised colours if required.
If repairing with long lasting woods where lack of maintenance is of primary importance then Teak is king. Iroko a good choise, Cedar the best option of the bunch if size of glazing components is of no great importance.
If " white painting required", use pressure treated timber( redwood/pine) in combo with aluminium primer
Middi

 

[Pford75]

Middi - Thanks for the response.

The greenhouse in question is a lean-to 'working greenhouse' - in other words, aesthetics are less important. It will not be heated and is really only used for spring-autumn growing. One of the key aims is to make it as maintenance free as possible as there is simply too much other stuff to do, without adding to the list.

The existing structure is in some kind of softwood (very soft in some parts). The timbers which have been kept dry (under the roofing) are sound, whereas the South facing wall is virtually all rotten and unsaveable. The greenhouse is built on a dwarf wall with a long South face and two shorter East and West faces. The roof and East/West faces have been covered with Corolux which has reached the end of it's life.

My plan was to remove the South timber frame and prop the roof. I would then insert a new South frame (basic 'grid' construction with glazed panels retained by beading), and then replace the roof in polycarbonate and the ends with glazed panels. There will not be any 'glazing bars' as each panel will be retained by 25mmx25mm square bead. (I'm not an expert woodworker like yourself, so I wanted to make the construction as simple as possible )

Would Oak be suitable in these circumstances? I'd like to leave it unpainted. If not, is Sapele a suitable alternative?

 

[middi]

Due to the fact that you intend to use polycarbonate glazing I would repair it ( or create a new section) by using cedar. An ideal wood to use when there is some worry about the weight of glass. Cedar is as rot proof as you can get, bar teak, it does not need any maintenance or any treatment for it to perform for 40+ years. It is also reasonably priced and soft to work with - highly repellant of rain and insects attack due to it's very high natural oil content.

American white Oak will rot before cedar and difficult to obtain in " cuts" that will not "warp". European " selected cuts" or english oak , if it can be obtained, and teak are obviously very good, also more expensive

Iroko and sapele are also very good, if oiled, and only better than Cedar from a strength point of view. If strength of wood is not very important then the choise should be Cedar as this wood performs just as well when not treated or oiled.

Middi

 

[Penners]

Pford - it occurs to me that, if you choose to use a special section of timber machined to your requirements (no matter what timber you choose) then you might as well have the rebate(s) machined in by the supplier. If he's already machining the timber to your spec. he's unlikely to charge you much more to run the rebate(s) at the same time. If he's decently equipped it will simply be a matter of setting up a different-shaped cutter in his machine (which is called a "four-cutter").

I should certainly investigate this with your chosen supplier. It would save you planting on all that beading.

 

[Pford75]

Ive started clearing out the old greenhouse in preparation for the work. There is an old cast iron heating system which was badly corroded in several places where it was exposed to the weather. Anyone know if it is possible to get replacement parts or should I look to scrap?

 

[Penners]

If the parts are small enough to get in your car, you might nip into your local plumber's merchant and ask. Otherwise, how about architectural salvage yards?

 

[Flyfisher]

What sort of 'part' need replacing? I'm pretty sure that cast iron pipework and fittings are readily available, though I'm not too sure about old boiler parts. Best to find a 'proper' plumber's mecrchant though, if you know what I mean.

Of course, a lot depends on how much you wish to spend. An old mechanical engineering friend used to work in power stations and now restores traction and steam engines. It seems fairly easy for him to find all manner of bits and pieces when needed and when he can't then he seems to be able to make a replacement.

As an old builder once said to me "it's only a matter of money . . . we can put a man on the moon if you have enough money". :lol:

 

[LadyArowana]

As an old builder once said to me "it's only a matter of money . . . :lol:

*sigh* if only it was that simple, I would really like a ladies Taisho era, yuzen dyed vintage kimono jacket, in very good condition, with elephants on, in nice colours.

 

[Penners]

I would really like a ladies Taisho era, yuzen dyed vintage kimono jacket, in very good condition, with elephants on, in nice colours.

If only you'd said before, Milady. We dressed our guy in one of those, last Bonfire Night.

 

[LadyArowana]

I would really like a ladies Taisho era, yuzen dyed vintage kimono jacket, in very good condition, with elephants on, in nice colours.

If only you'd said before, Milady. We dressed our guy in one of those, last Bonfire Night.

:lol: :lol: :lol: well, at least that gives me hope that they were made! so I shall carry on looking.

 

[middi]

Ive started clearing out the old greenhouse in preparation for the work. There is an old cast iron heating system which was badly corroded in several places where it was exposed to the weather. Anyone know if it is possible to get replacement parts or should I look to scrap?

4 inch cast iron pipes were quite popular for commercial ( and home) greenhouse heating untill the early 60's. These were, in the main, heated by a main boiler sunk below the level of the 4 inch flow and return gravity fed pipework. Coal being the main fuel.
For new installation, from that period, smaller bore steel pipes were used ( 2 inch) consisting of adequate numbers of flow and return pipes to satisfy heat requirement. These were heated by gas or oil and easily controlled therefore more efficient heat distribution. Mostly warm air nowdays.

You can certainly easily get 4 " cast or aluminium pipes which can be connected with rubber sleeve connectors, as to traditional male to female connections cast iron pipes I am sure they are specialist order only.

Middi

 

[Flyfisher]

My understanding is that the threads for iron pipework was usually cut on site as needed, so if you're really intending on reusing it you'll probably need the appropriate dies. I've no idea about the thread type, though I have a friend who would probably know.

The remnants of the old heating system in our house is large bore iron pipe, though nearer to 3-inches than four. I'll be removing it all at some stage but could probably be persuaded to do it sooner rather than later if you could find a use for them.

 

[middi]

The four inch cast iron heating pipes of yesteryear were male and female ended for long runs and a double ended female " boss" used to join short runs of pipes.

The joints had at least a quarter of an inch clearance to allow " packing" with rope and cement.

Middi

 

[Penners]

My understanding is that the threads for iron pipework was usually cut on site as needed, so if you're really intending on reusing it you'll probably need the appropriate dies.

I believe hire centres often offer tap-and-die sets.

 

[Pford75]

Thanks for all the responses. Middi is correct - the pipework was 4" cast iron, although there were no male/female ends, they were all joined with some sort of collar joint which appears to have contained some sort of rubberized gasket. These gaskets have now perished and on closer inspection, the pipework was badly corroded and the boiler which was situated 2 feet lower in the potting shed is literally falling apart. I've decided that it will have to go and we will look towards warm air heating. The pipework is now out and I have begun clearing in preparation for the construction work.

I'm taking Middi's sage advice and have gone for cedar. The roof will be twinwall polycarbonate (mainly for safety reasons) and some of the end panel will be polycarbonate (due to ease of cutting to shape and ability to fit large sheets). I have attached some photos below. The left hand side will have the front glazed section removed and replaced. The roof structure appears sound, so hopefully I intend to retain that (with some minor repairs). The right hand section of the greenhouse had disappeared before we bough the house, but I believe there used to be some structure there...largely because the heating extended into this area as well and there is evidence of door fixings on the threshold as your enter this section. Will post further updates as things progress...but for now, I'm waiting for materials and for the weather to warm up slightly.

BTW - One of my team at work is based in Moscow. She reported that it reached -25C on Tuesday night :shock:

 

[Penners]

we will look towards warm air heating.

I suppose heating is essential, is it? We've had greenhouses at every house we've lived in, but never had heating in any of them. I should add that we don't overwinter terribly tender plants, but we've normally managed to get pots of geraniums and suchlike through the winter in there. And Mrs P often starts off half-hardy stuff in the greenhouse early in the year.

I'm taking Middi's sage advice and have gone for cedar.

Good choice!

The roof will be twinwall polycarbonate

Have you compared this with the cost of triple-wall? I was just wondering whether some extra investment now in that additional roof insulation, plus double-glazing in the front windows, might be a worthwhile alternative to the ongoing cost of heating the building.

 

[middi]

If you need the cedar to maintain that dark red( ish) vibrant colour, instead of the silvery patina that the surface of cedar will eventually revert to, before you install the glazing give the glazing bars a coat of " cedar" preservative ( more of a stain, actually, than a preservative function). This oil bases stain will penetrate extremely well into the soft textured surface layer of the wood and will maintain that vibrant colour for at least 15 years. You can always give it another coat after 15 years if you want to :wink: .

I dismantled a cedar greenhouse which was used for orchid growing for 18 years and the cedar stain, which I had applied when i assembled it, was nearly intact In the rebates of the glass glazing . Remembering that orchid growing is an extremely humid environment.

Middi

 

[middi]

Following Penners suggestion regarding the need for heating, the home greenhouse is usually divided into five main ctatagories of use where temperature is concerned, Ie- " cold house" when no heating is introduced and normally just used as an extended growing season and possibly early sowing with the aid of a heated or unheated propagator ( depending on variety seedlings). Also used to overwinter the less hardier plants that usually only do well in meditarrenean climates.

The " cool" house, where the temp is not allowed to drop below ( about ) 4 deg C, giving a much wider variety of plants averwintering and growing

The " intermediate" house, when the temp is not allowed to drop below 7 or 8 deg C with at least a 5 deg C increase of temp during daytime hours, this allowes for growing a wide range of tropical and subtropical range of plants.

The " warm house" , where temp does hot drop below 11-13 deg C

The " hot house" , steamy jungle condition min temp 21 deg C.

Middi

 

[AMc]

Late to the thread - we have a large glass living room constructed on the footprint of a Victorian vinery.
The double glazed roof is held in place with Exitex capex - which is a sandwich of rubber gaskets holding the glass held in place with a screw down powder coated strip which is turn has a slot in cover for the screw cover.
This creates a glass and powder coated aluminium roof which should require no maintenance other than cleaning.
It looks modern but not horribly so and given the choice of repainting an 8x5m softwood and glass roof it seemed the sensible choice.

My stuff came from Mr Plastic in Norwich and wasn't viciously expensive. http://www.exitex.com/