Use the two diagrams immediately below to help explain how to measure to ensure you order the correct size for your project. 
Dome only - if the measurement from the outside edge to outside edge of your upstand is 600mm you will need a dome of at least 600 x 600mm.
Roof Dome with PVC kerb - Select a roof dome size that is the same size or bigger than the structural opening in your roof
2 kerb heights are offered, 150mm (Standard) and 300mm (Tall - select this option if you are adding insulation on top of the roof).
BS 6229: 1982, Code of Practice for flat roofs with continuously supported coverings, requires rooflights to incorporate upstands to raise the mat least 150mm above the uppermost roof surface to which the roof covering is bonded or dressed. The designer/ installer should ensure that the builders curb is at least 150mm high.
If you are installing additional insulation to your flat roof the 300mm curb allows the addition of upto 150mm insulation.
Returns
Please note, due to the nature of this product our standard returns policy does not apply. Returns will be subject to a restocking fee. The product must be returned in the condition it was dispatched in (i.e. in saleable condition in it's original packaging).
The lead times and delivery service are displayed against each product, just below the price.
We will continue to send items on a Next working day delivery, but please accept delivery might take longer, this is out of our control.
Please note, for certain products and delivery zones we can offer AM deliveries and Saturday Deliveries, if available, you'll be able to select and pay for these options via the checkout.
Delivery Charges will be applied for deliveries to geographical areas represented as Zones C and D:
This includes certain parts of Scotland, Scottish Islands, Northern Ireland, Channel Islands and IOM)
We only supply to Trade Account Customers in Zone E
Cancellations:- Any stock item which is cancelled after having been dispatched, but before you have received it will be subject to a minimum fee of £25.00 + VAT for parcels and a minimum of £70 + VAT for pallets. Bespoke (made to measure) orders cannot be cancelled once ordered.
Returns:
You can return a standard product (most access panels, loft hatches, accessories and Steel / Aluminium Roof Hatches) within 14 days of receipt. Roof domes, Roof Lights, Glazed Roof Hatches and AOV Smoke Vents will be subject to a collection restocking fee.
Please note Made to measure products cannot be returned.
Click here to download a return form.
