It’s no secret that modular construction is the new wave being adopted by the big players in the construction industry. Skill shortages and fast-track programmes are amongst the primary reasons causing this trend to take shape. SIPs have emerged as the automatic product of choice from the housebuilding contingent; commonly this is becoming the case for garden offices too – but let us stop and explore the functionality of SIPs before you decide on a garden office.
SIPs are simply insulation sandwiched between OSB. The question is – where is the strength in terms of joists between those panels? – There aren’t any. Furthermore, these are expensive. OSB comprises crossed-layers of wooden strips compressed and bonded together, and when subjected to moisture can result in an irreversible swell – not an area you should drive fixings through unless you want your ceiling to come crashing down. Swelling up with costs and water, they aren’t the best material to be left to the harsh outdoors.
I hear you ask “but OSB 3 is waterproof right?” The answer…. It still swells when subjected to moisture, the swells lead to cracks and permanent, irreversible damage.
Recommendations are given by manufacturers to store SIPs in a safe manner to prevent moisture entry, but if you have any experience on a building site you would arrive at the conclusion that recommendations can fall on deaf ears. Throughout my almost 2 decades of construction experience I have frequently seen sloppy workmanship on a Friday afternoon before the obligatory Pub session. For roofing this can be unprotected SIPs which readily drink the rain or even worse… a rushed single layer of waterproofing overlaying the SIPs.
To combat the dwindling skills in the market it is crucial that you select a roof system which is quality assured in a way that you are satisfied. Afterall, roof leaks are one of the most common construction defects. At We WFH, we always use high grade timber rafters which are sandwiched between plyboard to provide proven strength. Plasterboard is directly fixed through a vapour control layer penetrating the timber joists to keep the load path direct rather than screwed into 11mm of potentially soggy OSB.
To allow ventilation around the timber frame, we adopt an innovative system of steel channels and corrugated cladding overlaying a TRIPLE WATERPROOFED deck – may I just add that this is quality checked by a Chartered Professional to add that seal of approval. In using a galvanised steel cladding we offer that extra protection compared to comparable products like the EPDM rubber roofing which has a long history of being savaged by hungry birds – a sure fire way to drain your bank account.