Can My Conservatory Take the weight of a New Roof?
When choosing to improve your conservatory roof it is very important to consider structural integrity. A conservatory is designed from the roof down. This means that the original supplier of the conservatory would have sent their measurements and specifications of the window and door system that make up the conservatory together with the brickwork or base-work and footings being used. All this information is sent to the roof manufacturer so they can design a roof that is fit for purpose.
Conservatory Roofing bars are made of aluminium and are designed to take the weight of double-glazed glass units, even if you have polycarbonate panels. Double-glazed units weight 22kg per square meter. As long as whatever you replace the glass with is less than 22kg per square meter, the conservatory will be fine. Our insulated panels weight 6.3kg per square meter and our multi-layer insulation weights 0.7kg per square meter. Our roof tiles weight 8.5kg per square meter. Making a total weight of 15.5kg per square meter. Do not leave the glass in place and clad over with roof tiles or add multi-layer insulation and cladding to the underside. The aluminium roof is not designed to handle the extra weight.
Some suppliers are building conservatory replacement roofs out of timber. Using wooden trusses fixed to wooden ring beams screwed to the Upvc window and door frames. They then use wooden battens across the roof and attach plastic roof tiles. On the inside they again use wooden battens and plaster board and plaster ceilings. This is much heavier than the original window and door frames were designed to bear. Upvc window and door frames that make up the conservatory are only designed to take the weight of an aluminium roof with glass or polycarbonate sheets. To use a timber constructed roof of this nature there must be RSJ supports keeping the load off the window and door frames as you would in a house otherwise, over time, the Upvc window and door frames will buckle, causing the locks and hinges to fail. This extra weight will cause the double-glazed units to blow and mist up.
The aluminium used in your conservatory roof is very valuable as scrap. These companies sell your aluminium to cover the cost of the wood which is much cheaper. Aluminium is far more stable and structurally stronger than timber, it doesn’t absorb moisture and is therefore not prone to over expansion and contraction which happens in a conservatory. Excessive timber movement will result in internal plaster ceilings cracking over time. Timber absorbs moisture leading to condensation and with the lack of ventilation in these roofs will lead to rot. Aluminium lasts a lot longer than timber and will not decay.
Some manufacturers are supplying kit form tiled conservatory roofs with plasterboard interiors as options for new conservatories. As mentioned before, the installer will send the information regarding door and window frames and building base work to the manufacturer so they can design the conservatory from the roof down and make sure the frames can withstand the weight of the roof. These roofs are not designed to be dropped onto existing conservatories. Manufacturers will not guarantee the structure of an existing conservatory. This is something that many installers fail to mention when selling the roof only.
Conservatory Roof Panels?
Another option is to replace the conservatory glass or polycarbonate sheets with Upvc panels and leave the original conservatory roof bars in place. Upvc flat panels have two 4mm outer skins and are filled with polystyrene to make up the thickness of the glass or polycarbonate they are replacing, 20mm – 28mm. The polystyrene is white in colour. There is another name for this type of insulation material called Styrofoam and it is blue. They are both polystyrene as Styrofoam is a brand name.
Polystyrene is a fair insulator with a U-Value between 0.8 -1.1 W/m2K. They are used in the flat panels you see in the bottom of a Upvc door, but they do not offer enough insulation for a roof. If replacing a five chambered polycarbonate roof sheet or a double-glazed glass panel, which is filled with argon gas, replacing those with a panel made from polystyrene or Styrofoam could make the roof less insulated.
To overcome this issue some companies are offering a system that uses a thicker polystyrene infill. Unfortunately, they then wrap the polystyrene in an aluminium box. Aluminium is a poor insulator as it is a conductive material. Any heat or cold from outside or inside, will be transmitted across and around the surface to the opposite side. Known as thermal bridging. That is why in modern double-glazed units they do not use silver aluminium spacer bars between the two panes of glass as it allows heat and cold to cross. Nowadays, double-glazed units use plastic spacer bars, sometimes called composite, as plastic is an excellent insulation material and it is non-conductive.
These companies quote the insulation figures of the thickest part of the panel which is 75mm and do not mention the overall insulation. In order to fit into the existing conservatory roof glazing bars the thick part of the panel stops short of the conservatory roof glazing bars by as much as 30mm on either side and as much as 80mm on the edges, returning to a panel thickness of the original roof glass or sheets it is replacing so they can fit into the glazing bars. The roof glazing bars are not insulated so about 100mm is very poorly insulated at the glazing bars and 80mm badly insulated at the roof edge. As heat goes to cold, your valuable heat will escape around the very poorly insulated sides of these panels.
Can I Replace the Conservatory Roof myself?
The cheapest way to insulate a conservatory roof is also the most dangerous. As mentioned before, conservatory roofs are not load bearing. They use the weight of the polycarbonate sheets or glass units to push down and clip into the glazing bars of the conservatory. This push down effect seals the glazing bars against the roof material preventing rainwater getting in.
Some suppliers are advocating screwing wooden battens to the underside of the glazing bars and then stapling multi-layer insulation to the underside of the conservatory. Multi-Layer insulation is an excellent insulator. It is also very heavy. You must not screw anything into the underside of the conservatory roof glazing bars as they are sealed boxes and designed to channel rainwater away from the roof. Screwing into them from below will cause a leak. These companies then add a second wooden batten to the underside of the first wooden batten and then screw on pvc cladding. This total weight will pull down on the conservatory roof causing the glazing bars to open up the rubber seals that push against the glass or polycarbonate roof sheets allowing rainwater to enter.
Conservatory Roof Upgrade – Do You Need Building Control Approval or Planning Permission?
No, you do not need Building Control Approval or Planning Permission to change your conservatory roof. Conservatories are exempt from Part L Building Regulations, (Conservation of Fuel and Power). However, it is always a good idea to reach the minimum standards for a conservatory roof installation. Our conservatory roof system surpasses the minimum requirement of Building Regulations even though it is not required to do so.
A Building Control Certificate of Completion is not required, however, showing evidence that your new roof meets thermal efficiencies will be crucial information for potential house buyers and when securing additional funds or mortgages for the property. If you do not have the specifications showing thermal efficiency of the new conservatory roof it may prove difficult to sell the property. All our installations come with full specifications showing thermal efficiencies tested by independent authorities such as the British Board of Agrément (BBA).
Now you can have a beautiful, insulated conservatory that you can use the whole year round. Visit the review page to read our success stories. Call to arrange a free survey and quotation on 0800 865 4465 or email us at help@conservatoryroofs.info