Custom Trapezoidal Angled Multi-Slope Outdoor Cover | Waterproof Design 21 (Made to Measure)
Custom angled / multi-slope outdoor cover – Design 21
Some outdoor items aren’t simple rectangles – they have sloping faces, angled fronts and uneven tops. Our Design 21 angled / multi-slope cover is made to measure for exactly that sort of shape, so you can protect complex storage boxes, equipment housings and custom garden builds with a cover that actually fits.
Follow the diagram and enter four key measurements in centimetres. We’ll then cut and sew a waterproof cover that follows the angles: lower at the front, higher in the middle, and tapering neatly towards the back. A small tailoring allowance is built in so the cover slides on easily without looking baggy.
How Design 21 works
Measure in cm along the dashed lines in the sizing diagram:
- (1) Height – vertical height from the ground to the highest point at the centre front.
- (2) Top depth – the distance along the top from the front break to the back edge.
- (3) Overall base depth – the full depth of the base from very front to very back.
- (4) Side length – the sloping side length from front to back on the long side.
The cover is patterned so the front panel is lower, the centre panel rises to your full height, and the sides follow the same sloping lines you see in the diagram.
Typical uses for Design 21
- Irregular garden storage boxes with sloping lids.
- Custom-built timber housings or pump covers.
- Angled log stores and coal bunkers.
- Equipment or machinery with an offset sloping top.
- One-off garden builds where a standard rectangle won’t fit.
Outdoor fabrics to suit your setup
Tier 1 – PVL 600D Vinyl-Coated Polyester
- Tough, waterproof and great value.
- Ideal for everyday UK weather and partially sheltered areas.
- Perfect if the cover is used mainly spring–autumn.
Tier 2 – P500UV Premium Polyester (PU + UV coated)
- Extra UV and weather protection for year-round exposure.
- Best for south-facing, coastal or very exposed gardens.
- Recommended for high-value equipment and permanent structures.
Our live calculator uses your measurements to estimate the surface area of the multi-slope shape and then shows an instant price for each fabric tier.
Tie-down options
To keep your angled cover secure, especially in windy or exposed spots, you can choose from several tie-down upgrades:
- No tie-downs – simple drop-over cover for heavy or sheltered items.
- Elasticated hem with cord lock – pulls the base in snug around the shape.
- Grommets & cord – reinforced eyelets and cord to tie to rails or anchors.
- Webbing straps with buckles – pass underneath key points for maximum security.
Why choose a Shiny Sofas custom multi-slope cover?
- Made to measure from your exact angled dimensions.
- Waterproof & UV-resistant outdoor fabrics built for UK conditions.
- Clean, tailored look that follows the slopes instead of fighting them.
- Optional image upload so we can double-check complex builds before cutting.
- UK-based support if you’re unsure which design is best.
Caring for your cover
Brush off loose dirt regularly, then sponge clean with mild soapy water and rinse. Allow the cover to dry fully before putting it back on. Avoid harsh chemicals or machine washing, as these can damage the waterproof and UV coatings over time.
If you are not sure whether Design 21 is the best layout for your shape, simply upload a clear photo with your order or contact us and we’ll be happy to advise.
💳 Pricing & Payment Information
The price shown above is an instant estimate based on the measurements, fabric and options you select.
At checkout, a standard base price may be displayed — this is normal and is used to place the order.
✔️ Your final price is calculated from your measurements, as shown in the price estimate on this page.
✔️ Any difference is confirmed before production begins.
✔️ If an adjustment is required, we will contact you or issue an updated invoice before sewing starts.
By placing your order, you confirm your measurements and acknowledge that custom-made items are priced according to size and specification, not the base product price.
How the tie-down options work
Choose the tie-down style that best suits your garden and wind exposure. All options are sewn to order on your cover.
- No tie-downs – simple drop-over cover, ideal for sheltered areas.
- Elasticated hem + cord lock – shock cord sewn into the base with a toggle to cinch tight.
- Grommets + cord – reinforced metal eyelets around the base with cord to tie to posts or anchors.
- Straps & buckles – webbing straps run under key points of the base for maximum security.
You can see close-up photos of each option above in the product gallery.
Questions about this custom angled cover?
Send us your question using the form below and we’ll reply by email. We’ll also add common questions and answers here to help other customers.
Frequently asked questions
Is Design 21 the right template for my shape?
Design 21 is intended for items with an angled or multi-slope top – lower at the front, higher in the centre, and tapering towards the back – with the base sitting roughly rectangular. If your item is a simple rectangle or wedge, another design may be more suitable.
Are the fabrics fully waterproof?
Both fabric tiers are designed for outdoor use. Tier 1 (PVL 600D) is waterproof for everyday garden use, while Tier 2 (P500UV) adds an extra PU and UV coating for maximum water resistance and long-term exposure.
What if my measurements are slightly wrong?
We add a small tailoring allowance to help the cover slip on easily. If you realise you’ve measured incorrectly, contact us as soon as possible with your order number – if production hasn’t started, we can usually update the sizes.
Can you add cut-outs or zips?
In many cases we can add simple cut-outs, flaps, vents or access zips. Upload a clear photo and describe what you need in the notes – we’ll confirm what’s possible and whether there is any extra cost before we sew your cover.
How do I clean the cover?
Brush off loose dirt regularly, then sponge clean with mild soapy water and rinse. Avoid harsh chemicals or machine washing, as these can damage the waterproof coatings over time. Always allow the cover to dry fully before storing.
Popular sizes & example prices
These examples use our live pricing calculator and show what typical angled covers cost with both fabric tiers. Enter your own measurements above for an exact price.
Prices shown include fabric cost and our minimum order charge where applicable, based on a simple drop-over cover with no tie-down upgrade.