What a replacement quotation should contain

What should be itemised

1. The unit: manufacturer, model, size code and glazing specification. Not “supply and fit rooflight”.

2. The flashing kit, and which profile. Where cheap quotations economise, and a flat kit on a profiled tile leaks.

3. The insulation collar. A separate order line, frequently omitted, and its absence shows as reveal condensation months later.

4. Access. Scaffold or tower, and who provides it. A quotation silent on access for a first floor window is incomplete.

5. Making good, to what standard, and whether decoration is included. Usually it is not, and it should say so.

6. Disposal of the old unit.

7. Building Control, where notifiable, and who notifies.

8. The contingency for decayed timber, with an indication of cost. Its absence does not mean the risk is absent.

Questions worth asking

Is the U-value whole unit or centre pane. Is the flashing kit correct for my covering. Is an insulation collar included. What happens if the timber is soft. Who notifies Building Control.

Guarantees

Two separate things: the manufacturer’s warranty on the product, and the installer’s guarantee on the workmanship. Most problems are installation problems, so the second is the one that matters.

Why the cheapest is cheapest

Usually one of: no scaffold where scaffold is needed, no insulation collar, a generic flashing kit, or no allowance for making good. None is visible on the day and all surface later.

Eight lines

Quotations for the same rooflight replacement can differ by a factor of two, and the difference is almost always in what is not written down. These are the eight items that should be named.

1. The unit

Manufacturer, model, size code and glazing specification, including the whole unit U-value rather than the centre pane figure. Without the size code you cannot tell whether you are being quoted a stock size or a made to measure one.

2. The flashing kit

Which profile, by name and part number, for your covering. A flat kit on a profiled tile leaves voids that water finds within a season, and it is the most common installation fault we find. A quotation that cannot answer this has not been written from a survey.

3. The insulation collar

A separate order line, frequently omitted, and its absence shows as condensation on the plaster reveal months later when nobody connects the two.

4. Access

Tower or scaffold, who provides it, and whether a highway licence is needed and included. This is the item that most often surprises people and it is the largest variable between two quotations for the same window.

5. Making good

To what standard, and whether decoration is included. Cheap quotations frequently stop at the plasterboard, leaving you a taping and skimming job to arrange yourself.

6. Disposal

Of the old unit, the old flashings and any broken tiles. A sealed glazing unit is not something you can put in a household bin.

7. Building Control

Whether the work is notifiable, by which route, and whether it is included. A quotation silent on this has left the notification to you, and that surfaces at the point of sale rather than the point of fitting.

8. A stated contingency

For decayed timber, with an indication of cost. On a unit that has been failing quietly for years it is a realistic possibility rather than a remote one, and an honest quotation names it rather than producing an invoice for it afterwards.

The two guarantees

Separate cover from separate parties, and both should be stated. The manufacturer warrants the product; the installer guarantees the workmanship.

Most rooflight problems are installation problems rather than product failures, which is why the second matters more, and it is the one most often missing from a cheap quotation.

Where cheap quotations save money

Three places, none visible when the job is finished: a universal flashing kit, no insulation collar, and making good that stops short. A fourth on replacements: forcing a modern unit into an old opening and packing the difference, which survives about a year.

The lines that should be separately identified

The unit. Manufacturer, model, size code, operation, and the full glazing specification including the whole unit U value, the g value and the spacer type.

The flashing kit. Named, with the profile stated, and matched to your actual covering rather than a generic one.

The insulation collar. This is the line most often missing, because it is an optional accessory that becomes invisible the moment the flashing goes on. Ask for it by name.

Access. Whether scaffolding is included, and if so what type and for how long. On a small job this is frequently the largest single item.

Making good internally. Plastering the reveal, and whether decoration is included or left to you.

Removal and disposal of the old unit and the old glass, which is not free.

VAT, stated rather than implied.

What should be said about the unknowns

Timber condition around an old opening cannot be established until the unit is out. A good quotation carries a stated provisional allowance for repair, so that finding soft timber is a priced variation rather than a stoppage and an argument.

The same applies to breakages in the covering on a roof of age.

How to read the cheap one

Where one quotation is noticeably lower, find the difference before assuming it is efficiency. It is usually the collar, the access, the making good, or an obsolete size being packed out rather than properly resolved.