What drops out of the price when you buy supply only
A supply-only price is for a product delivered to your kerb. Everything after that is yours to organise, pay for and stand behind.
Written out in full, the list is longer than most people expect, and several items on it are things you cannot buy back later at a sensible price.
- Labour to remove the existing unit
- Disposal of the old door, frame or window
- Packing and fixing the new frame plumb and square
- Internal and external sealing
- Making good plaster, render and brickwork at the reveal
- The building-regulation compliance certificate
- The installer's workmanship guarantee
- The insurance-backed guarantee on the whole installation
The building-regulations problem
Replacement windows and external doors in England are controlled work under the Building Regulations. There are two legitimate routes: the installer self-certifies through a competent-person scheme and issues you a certificate, or you notify your local authority building control and pay for an inspection.
With supply and fit through a registered installer, that certificate is part of the job and it arrives after the work. With supply only and a general builder, it is on you. People discover this at the point of sale, when a conveyancing solicitor asks for the certificate and the seller can't produce it. Retrospective regularisation is possible, but it costs and it delays.
Where the guarantee goes
This is the part that decides most cases. With supply and fit, one company is responsible for the product and the installation. If a door drops, it doesn't matter whether the cause was a hinge or a frame that wasn't packed — it's the same phone call.
With supply only, responsibility splits. A manufacturer's warranty on a door almost always excludes defects arising from incorrect installation, and the most common faults on doors and windows are installation faults. So the door drops, the manufacturer says it was fitted wrong, the fitter says the door was made wrong, and you're in the middle holding two invoices.
| Supply only | Supply and fit | |
|---|---|---|
| Headline price | Lower | Higher |
| Fitting labour | Paid separately | Included |
| Removal and disposal | Your problem | Included |
| Making good | Your problem | Included |
| Building-regs certificate | You arrange it | Issued with the job |
| Who's liable if it fails | Disputed | One company |
| Insurance-backed guarantee | Not available | 10 years, registered to the address |
The measuring risk nobody prices in
Made-to-measure means made to the measurements someone gave. On supply and fit, our surveyor takes them and any error is ours to correct at our cost.
On supply only, the measurements are yours. A door frame ordered 10mm too wide cannot be trimmed; it's scrap, and it's non-returnable because it was made for you. That single risk is why we won't supply-only on bespoke sizes without being very clear about who owns the dimensions.
When supply only genuinely makes sense
It makes sense when you already have a competent joiner or builder on site doing other work, when the opening is a standard size, when you're happy to arrange building-control notification yourself, and when you accept the split liability with your eyes open.
It also makes sense for internal work, which isn't controlled, and for non-critical outbuildings. What we'd steer people away from is supply-only on a main entrance door or on a full house of windows, where the compliance and the liability both matter and the saving is proportionally smallest.
Doing the sum properly
To compare fairly, take the supply-only price and add: the fitter's day rate for the time the job actually takes, skip or tip charges for the old unit, materials for sealing and making good, a plasterer if the reveal needs it, and the cost of a building-control application if no competent-person scheme is involved.
Do that honestly and the gap against a fully fitted price narrows a long way. Our fitted prices — uPVC doors from £799, composite from £1,099, French doors from £1,499, windows from £450 — are all complete-job numbers with every one of those items already inside them.
What to ask any company offering both
Ask whether the supply-only price is for the door alone or the door and frame, whether the hardware and cylinder are included or extra, and whether the glass is fitted or supplied loose.
Then ask what happens if the unit arrives damaged or wrong. On a fitted job that's our problem and our reorder. On a supply-only job, delivery damage claims have short windows and are your responsibility to spot before the driver leaves.
Insurance, and the question nobody asks until later
Two policies matter here and neither belongs to you. The installer's public liability cover protects you if something is damaged or someone is hurt while the work is done. Their employer's liability cover protects the people doing it.
On a supply-and-fit job through an established company, both are in place as a matter of course and you can ask to see them. On a supply-only job where you have engaged a fitter separately, that cover is between you and them, and if the fitter is working cash-in-hand it may not exist at all. A dropped frame through a bay window is not an academic scenario.
The third one is your own home insurance. Some policies expect structural or external alterations to be carried out by suitably qualified trades and to be compliant with the Building Regulations. An uncertificated window installation is unlikely to void a policy on its own, but it is one more loose end you have taken on in exchange for a modest saving.
Selling the house: where this comes back
Conveyancing is where supply-only decisions most often resurface. A buyer's solicitor will ask for building-regulation compliance evidence for replacement windows and external doors installed since the regulations applied to them.
If you can't produce a certificate, the usual routes are a retrospective regularisation application to the local authority or an indemnity policy. Both cost money, both take time, and both happen at the least convenient moment in a chain.
With supply and fit through a registered installer, the certificate arrives weeks after the job and goes in the drawer with the guarantee. Ours is issued through our competent-person registration and the guarantee is a 10-year insurance-backed one registered against the address, so both documents transfer with the property rather than with you.
Where supply-only does make sense
It would be dishonest to say it never does. If you are a competent tradesperson fitting on your own property, if the opening is a simple like-for-like in a modern house, and if you are prepared to own the measuring, the certificate and the warranty chain, supply-only can save real money.
It also makes sense on internal and secondary work — a porch door, a shed, a workshop — where no certificate is needed and the consequence of an imperfect fit is a draught, not a structural issue.
What we'd caution against is using it on main external openings to save a modest sum on the job that protects the front of your house and, one day, sits in a buyer's solicitor's enquiries. That is where the saving proves smallest and the risk largest.
Compare like with like
Send us any supply-only quote you've been given and we'll tell you exactly what it's missing against a fully fitted price. No obligation, no sales visit needed.