SIP panels can be a strong choice for extensions, annexes and habitable-style spaces because they combine structure and insulation in one system. The important difference is that these projects need clearer assumptions than a simple outbuilding.
Before you order, answer the questions below. They help avoid missed items, wrong thicknesses and unrealistic delivery or installation assumptions.
Is Building Control involved?
If the project is an extension, annexe, habitable room or dwelling-style build, assume Building Control or professional sign-off may be needed. UltraSIPs can supply SIP panels and kits, but structural calculations, approvals and site-specific engineering are separate unless specifically agreed.
Never rely on a budget quote as final engineering approval. The quote can include provisional physical support allowances, but calculations and final sizing must be confirmed by the appropriate professional route where required.
What SIP thickness is being assumed?
For habitable-style projects, 172mm is often a sensible starting point. 122mm may suit many garden rooms, but extensions and annexes usually need more careful thermal review. 222mm may be useful where higher performance is needed, especially for roof build-ups.
Use the UltraSIPs U-value calculator for early comparisons, then confirm final performance requirements with your designer or Building Control route.
Where are the openings?
Large doors, bifolds, corner openings and full-height glazing can change the support requirement. A quote should show whether openings have been allowed for and whether provisional beams, lintels, glulam or steel allowances are included.
If you already have structural calculations, send them with your drawings. If you do not, we can still produce a budget figure, but the assumptions must be clear.
What is excluded?
Typical exclusions include windows, doors, rooflights, cladding, foundations, drainage, electrics, plumbing, heating, plasterboard, Building Control fees and structural calculations. These may be added separately where needed, but they should not be assumed to be included.
Can the kit be delivered and unloaded safely?
Extensions and annexes can involve longer timber, more panels and greater total weight than a garden room. Vehicle type, site access and unloading plan need to be checked before delivery is booked.
UltraSIPs can quote delivery through the website or configurator, but unloading is handled by the customer unless an offload service is separately agreed.
Next step
If you have plans, elevations or even a rough sketch, send them through the UltraSIPs contact page. We will review the SIP package, thickness assumptions, openings and delivery route, then provide a practical quote with inclusions and exclusions clearly separated.