Diy Conservatory Garden Room

Garden Rooms and Sun Lounges

Planning Sun lounges and garden rooms
The structural problems at the heart of all conservatory conversions still exist when building garden rooms or sun lounges from scratch, but here at least the supporting structure for a solid roof can be designed in from the outset, traditionally by installing an arrangement of lintels and posts raised from dwarf walls to support the roof. Timber is the first material to consider for these elements, but it has the drawback of lacking strength in slenderness, so you need quite chunky section sizes to be able to use it. That’s fine where it fits in with your garden room design and the window frames can be set beside square posts 100-150 mm wide, but otherwise it can be tricky to accommodate them.

The alternative for a garden room is to use steel, which has a greater strength that allows more slender sections to be used. Posts can be 50 mm square hollow sections or tubes sitting on baseplates that are fixed down to the walls and headplates that are fixed above to the lintels. Effectively you are building a series of goalposts here, with crossbar lintels in a structural frame to hold up the roof. Some lintel companies have taken advantage of the sun lounge problem and designed a series of standard lintels and posts, prefabricated for easy erection on site. They’ve had to establish a range of standard sizes for these models, but do have designs for hexagonal and even curved ends, retaining some of the best and most popular concepts in conservatory architecture.

The hexagonal model has a continuous ring beam lintel that is mitred at the corners and supported by posts that are spigotted in the factory for easy installation on site. The curved or bow-fronted models inevitably have a minimum radius necessary for achieving the roof tiling and brickwork, but other, more simple designs, such as the standard bay window structure and built-in arches for circular or semi-circular windows, are just as effective on smaller sun lounges.

You can achieve all this with your own steel fabricator and fixer, but the steelwork has to be treated against corrosion and this is best done off site. Factory-made lintels are made from galvanised steel, often with a zinc coating (usually of at least 600 g/sq m) and all the edges are treated.

Cutting up lintels and steel on site means that the exposed edges are vulnerable to rusting, and painting steelwork with red oxide or galvanising brush-on paint just isn’t the same as having it factory dipped in the stuff.

In the fight against oxygen and its corrosive effects, any additional treatment is worthwhile, and some lintel companies also powder-coat their products with a thermally set polyester coat. As steel is very badly behaved when it comes to thermal insulation, whenever possible lintel companies insulate the core of their shaped lintels with polystyrene to reduce the cold-bridging effect that lets the heat out. All things considered probably manufactured lintels and posts should be used where your design allows you to.

As with any roof structure, these manufactured lintel and post arrangements rely on the roof being constructed to resist spreading: that is to say, it forms a triangle with ties (ceiling joists) joining the rafters together at their feet to restrain them. Without ties, the rafter feet will begin to make their own way out in the world and your roof will sag with their departure. If you were hoping to have a vaulted ceiling, as conservatories do, you will need to include some tie beams. Again, preformed cradles of steel can be included and concealed between the rafters to tie the eaves lintels via the ridge together. In this they have the advantage of achieving a totally uninterrupted ceiling space that can be plastered or boarded as you so desire.

If you want something to grow a vine over, you could always include a steel bar tying rod. Like those in conservatory design, the rods are threaded through the lintels and bolted to their outer faces, gathered beneath the ridge in a steel ring that also joins them to the ridge with a third stabilising bar. They are found in isolation in conservatory roofs, at least at far-apart centres, but remember that the solid roof represents a higher load and the spacing of these bar arrangements will be reduced. They can, with a few twists and some black paint, have a bit of architecture about them and tend to get used for the occasional hanging basket, appearing in this way to be more of an interior design feature than the reality of a structural intrusion.