Diy Conservatory Building Frame

PVC-u frame systems

Any conservatory must be designed to resist the elements, but choosing the correct conservatory frame and creating one with some additional robustness will ensure that it stays weatherproof for decades to come. Most conservatory frames are fairly compact in design, and the end panels are easily able to support the side ones against the pressure of the wind, but there is a limit to the span of the panels. If they are too long, the walls and roof may need to be strengthened with a steel or timber portal frame.

If you’re buying in your conservatory as a design and erect package, the supplier will take care of this design and should be able to provide structural calculations to justify it. The manufacturer should provide you with a structural guarantee for the superstructure in these cases. If, on the other hand, you are self-designing the conservatory, an engineer’s involvement should also be sought. The conservatory frame manufacturers should tell you what the limits are for their product- but as a rule of thumb, when conservatories exceed 6 m in length, you should at least check the limits.

Large conservatories and lateral stability
The weight of your addition will help to keep the conservatory in place but horizontal pressures are brought to bear as well and they don’t help at all. Horizontal loads aren’t so easy to take care of. They come from one of two sources: the wind or, in the case of basement and retaining walls, the ground. Wind loading can vary tremendously, and some method of calculating the maximum wind pressure on a wall has had to be derived by British Standards over the years. BS:6399 does this and allows the design engineer to pick basic wind speeds off the map appropriate for your region and then tweak them with a series of factors based on your home’s altitude and level of exposure or shelter. Whether the wall will stand up or not depends on the strength of the frame and masonry used, and the size of the panel between buttressing ends. This level of analysis is entirely unnecessary for standard-sized conservatories but for anything on the large size it becomes an issue.

PVC-u frames have a little metal tubing inside them for strength but this isn’t enough and wind posts may have to be added between the frames on larger models. These posts are hollow-sectioned steel posts that can be built in to the wall and tied top and bottom to transfer the load into other structural elements, such as the eaves beam or a cross tie. You can buy proprietary ones made of stainless steel, or you can get a steel fabricator to form one to suit your needs; often plastic-coated 75 x 75 mm SHS steel posts are used as part of a structural frame for large conservatories that would suffer structural damage otherwise. In England and Wales, large conservatories have always been described as being over 30 sq m in floor area, and approval under the Building Regulations has been necessary for these since 1985.

Apart from the thermal standards applied by these regulations, the other difficulty comes with the structure and the issues of lateral stability. If you’re buying a designed and manufactured package, the structural design calculations and details should come with it for this purpose. If you’re preparing your own design to be constructed, you’ll need the services of a structural engineer to calculate the loads applied and resolve the size of beams and ties for the frames. They may still be able to use frame analysis methods that will allow you to have “standard” frames prefabricated in steel hollow sections or timber off-site. This will be a tremendous help to your builders and speed up the construction process on site.

System-build assembly
Plastic conservatories have one major advantage over timber: they’ve seen investment in a system-build approach to make them quick to install on site. Some frame manufacturers have embarked on a bit of product evolution and invented new ways of fitting the parts together more simply and quickly, the aim being to pre-assemble much of the frame in the factory. A typical roof might arrive in 15 component packs for a standard-sized conservatory plus the glazing, but six packs plus glazing can often be achieved with system-build kits. Assembly steps that can only be taken on site are done with “snap lock” or “click fit” joints, which don’t need bolts, screws or silicone mastic, the prime elements of the erection process.

Speed of build might not be an issue if you’re not a housing developer, but system-build kits have a market with home owners embarking on DIY too. They make the process much simpler and some even provide the bits in colour-coded boxes to match a box-opening sequence. PVC cappings and finishings that cover aluminium pieces are neatly paired with them, and the instructions seem to be practically idiot-proof. This system leaves much less room for error and it is safe to say that the kits are much better designed, made and packaged than any flat-packaged furniture you’ve ever bought.

The systems mean that an average 3 x 3 m model can have its roof framed and glazed in one and a half hours on site, about half the time it takes using the bolt and silicone joint types. With some innovative components being patented by the designers, not all the systems are identical, and you need to shop around to find the easiest for DIY assembly. Some have spirit levels built into the ridge member which means you can be certain the piece in level. Most systems include some dual-purpose elements like a fascia board that also supports the glazing and thus does away with an eaves beam; or an eaves beam that doubles as a fascia, and so on.

Given the incompatibility between polycarbonate sheets of roofing and the soft metal of lead flashings, plastic flashings are also available. The ridge pieces are designed and made to lock in with stepped flashing pieces extruded from PVC, looking rather like preformed stepped cavity trays, that can weather the abutment between wall and roof.

Snagging
When the job is finished you can check it over and create a list of defects that need attention. In the industry this is standard practice and is known as snagging – a more onomatopoeic work you could not have found!

Cavity wall ties
For a very long time cavity walls were built with 50 mm cavities, until the 1980’s when we began to fill them with insulation. In 2002, when external wall insulation standards were increased to a maximum U value or 0.35 w/m sq k, wider cavities became standard to allow for a greater thickness of insulation. With these you can still use the standard wall ties at maximum 900 mm horizontal and 450 mm vertical spacings. If you want an even wider cavity, you should use a suitable tie, such as the vertical twist type, to maintain the structural bond, even for a low wall: for this, the maximum horizontal centres are reduced to 750 mm from the standard 900mm.

Cavity wall insulation
Don’t be tempted to miss out on the insulation of your cavity walls – the cost is negligible and it will help, in conjunction with an insulated ground floor, to reduce the heat loss from any conservatory. With dwarf walls, you can expect to see the inner leaf of blocks or bricks built first and the insulation attached to it before the external skin of facings goes up. Cavity wall insulation is installed in this way and is never pushed down into the cavity afterwards, even if the wall is low.

Matching bricks
Consider yourself lucky if you can find the same brick that your existing home was built with and it still looks the same. Bricks, like cakes, never come out of the oven looking identical, and there is some variation from batch to batch, let alone from year to year or decade to decade – all of which presents any addition to the home with a problem: do you plough all your efforts into looking for the nearest match, or do you go for a contrast?

The nearest match idea works up to a point. Many builders suggest that the colour will change as the brick weathers in and blends with the existing bricks but this is not always the case even after many years. After colour should come texture – not the other way around. A brick that has the same colour but a different facing surface won’t be so noticeable as one with the same texture but a different colour. Try this by obtaining several options in brick sample packs from your supplier. One brick is not enough; three or four are needed to see the potential for variation. Mix themand stand them up against the original and look at them in the half-light, in the sunlight and in the shade, and only then decide.

If you can’t find a brick that looks anything better than a bit different, it might be best to adopt a contrast and look for bricks that are obviously different. In this way, the contrast can be viewed as an architectural statement and not a failed case of matching in. For a contrast, you need colours that are in the same tone, and a colour wheel will help just as much here as it does in choosing paint and furnishings. A sandy, buff-coloured brick will not match so well with a red or orange facing as it will with a brown colour. Harmonious colours or those from the same tonal range work best together and if you are only building a few courses high, a deliberate contrast is often the most appropriate choice anyway.

Solid walls
When you consider it, a solid wall facing a boundary is not an undesirable thing and offers some privacy to both neighbours. It also gives some extra stability to the construction, as well as some valued sound and thermal insulation. If you are going to invite some plants into your conservatory to share it with you, a masonry wall will also store much of the day’s heat and release it gradually at night, as well as affording you the exciting opportunity of growing some exotic climbers. Every gardener knows that on a summer’s day a south facing brick or stone wall acts as a heat bank, but one behind glass will do an even better job throughout the year. In the Eden Project, the natural earth bank does the same and indeed the Biomes were positioned to take full advantage of this effect. A solid gable wall, boundary or no boundary, is not a bad thing at all.

Stone walls
Brickwork isn’t the only form of masonry; stone walls look terrific inside and out. If your home has been built with stone, it is likely to be indigenous to the area, and it’s important to source it locally to match in. Stonework does vary from region to region, not just in the type of stone but also in the way it is laid. If stone has a drawback at all, it is that the conservatory framework of windows around the perimeter means that the dwarf wall must be pretty much perfectly level at its head. Even when it is shaped and coursed, stone is hard to lay that level, so a thick mortar bed may have to be provided for the frames to be set on, and the projecting cills may need to hide it. Don’t be tempted to lay a dry stone face without the cavity behind it being designed to drain away large quantities of wind-driven rain – and stone isn’t always frost-resistant. Mortar spacing dabs aren’t really any better, as the mortar can transmit salts through to the surface to create efflorescence. This happens a lot with brickwork these days, but it does wash off and give up in time. Stones are best when they are bedded down flat on their natural quarry bed, and the quarry supplying it can mark this for you.

Where flint walls are to be formed, concrete blocks of standard and regular size that have flints set in the face are available. The stones project from the concrete surface so that when the block wall is built they can be pointed in carefully to lose the “block joints”. Using these blocks, you have both the level surface that you need for the frames and the rustic appearance of traditional flint walling. Even if your home doesn’t already possess flintwork, it can add a pleasing contrast to the brick walls of a country house.

Fielded or moulded panels
A cheaper alternative to building a dwarf wall uses panels as part of the framework. These are effectively solid windows, if that makes sense. Moulded PVC-u panels are extruded with polyurethane core the same as external doors in this material. They have good thermal insulation properties and allow the construction work to proceed much more quickly in the absence of any bricklaying or plastering. They can be easily washed down, will never rot or need decorating but will always look like plastic panels, at least in white. Mahogany or teak-finished PVC-u has a distinct advantage in this situation, as in panels it can look like real hardwood – well, from a distance in poor light!

In traditional timber construction panels, instead of being moulded, are fielded using either solid timber frames or plywood that is decorated with mouldings glued and pinned in place. The lower walls of any building are prone to rain splashing, accidental damage and general wear and tear, and this is not the place to skimp on durable construction. Some better quality timber framed conservatory manufacturers have switched to routing fielded panels out of 44 mm solid wood – the very material thickness used in the styles and rails of external doors. When the wood has been vacuum-treated with preservative, it can be guaranteed for at least 15 years. At the cheaper end of the market, softwood pine can be used and treated with stain to achieve a natural finish; at the top end you get hardwoods such as iroko. Whichever you choose, remember that timber of any kind in contact with the ground will be susceptible to damp and rot. The base plinth must include a DPM that is dressed over a DPC beneath the panels and their sole plates. Plastic is a DPC by itself, of course, but since damp can penetrate the gaps between panels if they aren’t totally sealed, it pays to use a DPC beneath them and to silicone-mastic the joints.

Steel framed dwarf wall kits are also available, very much the kind of construction popular in the United States, with lightweight galvanised steel channels bolted down to a steel tube base and clad over. They don’t rot, and they are totally vermin-proof because the panels are covered by ultra-thin steel-profiled sheets as well. The worst thing about them is they are designed to be faced up by a false brick veneer, much like the stone cladding we used to glue to our homes in the 1970’s. If you do use this panel system, you might want to show your home a bit more respect and replace it with render over expanded metal lathing instead.

Glass block panels and walls
Glass blocks aren’t new but they are back in fashion, notably in contemporary design and usually as internal screens, but they can also be used as panels for the external walls of a conservatory or sun lounge. They can be installed dry within a framework, and dedicated lightweight systems are available to this end, comprising an outer frame that can be fixed to the surrounding structure and both horizontal rails supporting the blocks and vertical dividers. You can use glass block walls inside – as dividing walls that let the light through but also provide excellent sound insulation from one part of your addition to another and in this respect they make ideal in-fillings to enlarged openings surrounding a door between the house and the conservatory – or outside. If you choose to use them for part of an external wall, it is important to drill out a series of 12 mm holes along the horizontal rails and the sill for drainage. Without it, they will act as collection channels for rainwater running off the glass fence. If your framework is in timber, it goes without saying that it should be treated with preservative.

Not only has the range of colours and finishes expanded with their popularity, but also the sizes of blocks. There are even ventilator blocks and end blocks, glass tile ends, corner and curved radius blocks on the list of extras because you can’t cut or drill glass blocks. In truth, about all you can do to alter them is sandblast them to create a more obscured finish and cut about 80 per cent of light transmission. Laying them couldn’t be easier. Armed with a small trowel for spreading the adhesive mortar, a level and a sponge for wiping them clean, anyone can build with glass blocks. All you need to check is that you are putting in the spacers and the work is level plumb and true as you go. Let the mortar set for an hour before you try to strike it off from where it has squeezed out of the joints and don’t let it dry out totally before you sponge any surplus off the face of the blocks themselves. The manufacturers also provide reinforcing bars which can be simply pressed down into the bed of adhesive before the next course of blocks are laid and these are essential for panels over a certain length (around 1400 mm) but highly recommended anyway.

If your panels are relatively small, you might prefer to build them first and install them to the frame opening later. Some of the dry-fix systems are designed for this but do remember that you are going to have to lift the finished panel into position and it is going to be heavy. The framing can consist of planed timber that slots into plastic sleeving for a clean and neat finish. Stainless steel anchor brackets and the use of silicon mastic for sealing around the perimeter and caulking the joints between blocks create a weatherproof panel. There are two uses that make glass blocks exceptionally superior to glass panes.
The first being that you can build a curved panel out ofthem very effectively. Of course there is a minimum radius for the standard size blocks to achieve this but it is only about 1650 mm and it would be easily achieved. The second is on the boundary walls where fire-resistance is required. A special glass block that has been tested and certified for this purpose is needed here, but they are commonly available as the only difference between them and the standard ones is a thicker wall of glass. Instead of the usual 8 mm, the walls of these are increased to 26 mm, making the overall block width 100 mm instead of 80 mm.