NOTE Nº 0240 · REV B

Who Buys the Materials: You or the Builder?

Should your builder supply materials or should you buy direct? Cost, VAT, risk, warranty and how to split responsibility.

By The Renovation Notes Team · 6 min read · Published 21 October 2025 · updated within the last month · Sources checked 30 September 2026

Two adults discussing home renovation in a partially constructed modern wooden interior.

In short

Builders usually add a markup to the materials they supply, often quoted at 10–25%; buying direct can save money but transfers procurement risk and warranty responsibility to you. Which approach works better depends on the project size, your time, and whether you have a trade account.

One of the most common questions homeowners ask when getting quotes is whether they should buy the materials themselves or let the builder handle everything. There’s no single right answer, it depends on the project, the contractor, and your own capacity to manage procurement. But understanding how each model works helps you make an informed decision rather than simply defaulting to whatever the builder prefers.

How Builder-Supplied Materials Work

When a builder supplies materials, they typically purchase through their trade account at a builders’ merchant, mark up the cost, and charge you the combined total. The markup covers their time sourcing and procuring materials, delivery coordination, and the risk of price changes between quote and delivery.

Trade markups on materials vary; 10–25% on top of the merchant’s trade price is a commonly quoted range for general building materials, not a fixed rule. On specialist or high-value items, kitchens, bathrooms, bespoke joinery, the markup can be higher, or the contractor may pass through the cost at near-trade price and absorb it as goodwill to keep a smooth project relationship.

From the builder’s perspective, supplying materials is normal practice. They know what specification is correct, they manage the delivery logistics, and they’re responsible for any defects that arise from incorrect products. Under the Consumer Rights Act 2015, goods a trader supplies to you as part of the job must be of satisfactory quality.¹ The work itself must be performed with reasonable care and skill.²

How Client-Supplied Materials Work

When you supply materials, you’re essentially taking on the procurement role. You buy direct from a merchant or retailer, at retail or, if you have a trade account, at trade prices, and the builder installs what you provide.

The potential saving is real. If you can access trade prices, the materials line in a quote can shrink considerably. But “supply and fix” contracts (where you supply, the builder fixes) shift a significant amount of responsibility to you:

If the materials are wrong, short-delivered, or damaged, you sort it, and if it delays the build, the cost of that delay may fall on you.
If defects arise after completion, the builder can argue that the materials you supplied were at fault, which complicates any warranty claim.
You’re also managing deliveries, storage on site, and phasing, all of which take real time.

The VAT Question

VAT is worth understanding here, though the rules are specific and you should verify your situation with an accountant or HMRC guidance.

On new-build and certain conversion projects, building materials supplied and installed by a VAT-registered contractor as part of a zero-rated supply should themselves be zero-rated, because a builder charges the same rate on the materials they supply and incorporate as on their work.³ Buy the same materials yourself and the merchant charges the standard rate, so the zero rating is lost on everything you hand over, though on an eligible self-build you can claim it back through the DIY housebuilders scheme.³

For standard refurbishment and renovation work, VAT on both materials and labour is normally 20%, so there’s no benefit in separating the supply in order to manipulate the VAT position.³ Two exceptions are worth checking before you agree who buys what. A contractor may charge 5% on renovating a dwelling that has been empty for at least two years.⁴ The same 5% applies to a conversion that changes the number of dwellings, and in both cases the materials the contractor supplies and fits follow the reduced rate.⁵

Comparing the Two Approaches

Factor	Builder Supplies	Client Supplies
Typical markup on materials	Often 10–25%	None (at trade)
Procurement time (your time)	Minimal	Significant
Warranty on materials	Builder’s liability	Your liability
Risk of wrong products	Builder’s risk	Your risk
Delivery coordination	Builder manages	You manage
Flexibility on specification	Less (builder chooses spec)	More (you choose)
Credit terms at merchant	Builder’s account	Your account

What Works Well as Client-Supplied

Some items work well as client-supplied because the specification is simple, the quantities are easy to manage, and installation isn’t affected by minor variation:

Sanitaryware, taps, and bathroom accessories
Kitchen units and appliances (fitted by a kitchen specialist)
Flooring and tiles (supplied, then fitted by the builder’s tiler)
Light fittings and switches (supplied, fitted by the electrician)
Decorative ironmongery and handles

These are mostly finish items where you want control over the specification and where delays in supply don’t hold up structural work.

What to Leave to the Builder

Structural and technical materials are usually better left to the builder to source. These include:

Concrete, blocks, bricks, lintels, quantities and specifications are tightly linked to the structural design
Roof felt, battens, and tiles, the builder needs to coordinate closely with the roofer
Insulation and airtightness membranes, specification must meet building regulations and is part of the builder’s compliance responsibility
Anything specified by an engineer or architect, getting the wrong product can have structural consequences

How to Split Responsibility Clearly

If you agree a split arrangement, set it out clearly in the contract or at least in writing before work starts:

List every item and mark it as builder-supplied or client-supplied.
Agree a programme, when does each client-supplied item need to be on site?
Clarify who pays for delays caused by late or incorrect client-supplied materials.
Agree on warranty terms, the builder should put in writing that their defects liability covers labour only on client-supplied items, and that they’re not responsible for failures caused by materials they didn’t select.

A well-written contract prevents most of the arguments that arise later. On large projects, a quantity surveyor or project manager can help draft a clear schedule of responsibilities.

The Honest Bottom Line

For most homeowners doing a single renovation project, the time and risk of client-supplying all materials isn’t worth the saving. The exception is where you have a genuine trade account, real experience managing deliveries, and the project is large enough that the material costs are substantial.

For specific finish items, tiles, sanitaryware, kitchen units, client supply is common, practical, and gives you more control over the specification. For structural and technical materials, leaving procurement to the builder is usually the smarter move.

References (5)

Figures in this note were checked against the sources below on 30 September 2026. Superscript numbers in the text point to them. Every source the site cites, by topic.

1technicalvery strongThe National Archives (legislation.gov.uk), legislation.RN-IHA647Section 9 implies into every contract to supply goods a term that the quality of the goods is satisfactory. s.9(2) sets the objective test: quality is satisfactory if it meets the standard a reasonable person would consider satisfactory, taking account of description, price and all other relevant circumstances. s.9(3) lists the aspects of quality where appropriate: fitness for all the purposes for which goods of that kind are usually supplied, appearance and finish, freedom from minor defects, safety, and durability. Durability is the limb that matters for building materials. s.9(4) excludes defects specifically drawn to the consumer's attention before the contract was made, defects the consumer's own pre-purchase examination ought to have revealed, and in sample contracts defects apparent on a reasonable examination of the sample. This is the base right behind any claim against a merchant for bad materials.
2technicalvery strongThe National Archives (legislation.gov.uk), legislation.RN-F06Z1FSection 49(1), in Part 1 Chapter 4 of the Consumer Rights Act 2015, states that every contract to supply a service is to be treated as including a term that the trader must perform the service with reasonable care and skill. Section 49(2) directs the reader to section 54 for the consumer's rights when that implied term is breached. This is the single provision that makes poor workmanship by a builder a breach of contract without the homeowner having to prove anything was written down, and it cannot be excluded to the extent it would stop the section 54 to 56 remedies applying.
3technicalvery strongHM Revenue & Customs, guidance.RN-KBNHMBHMRC's main VAT notice for building work, last updated 26 August 2026. Sets out that construction of a new building and work to an existing building is normally standard rated at 20%, with exceptions: 0% for new qualifying dwellings and for housing association conversions of non-residential buildings, and 5% for a 'changed number of dwellings' conversion (section 7) and for renovation or alteration of a dwelling not lived in during the 2 years immediately before work starts (section 8, conditions at 8.1.2 and 8.3). Cites the law: VAT Act 1994 section 30 and Schedule 8 Group 5 for zero rating, section 29A and Schedule 7A Groups 6 and 7 for the reduced rate. Also explains the developer input tax block on goods that are not building materials (VAT (Input Tax) Order 1992 articles 2 and 6) and points self builders to the DIY housebuilders refund scheme.
4technicalvery strongHM Revenue and Customs, guidance.RN-FX7S48The section that carries the 5 per cent empty home rate, which most renovation budgets miss. A contractor may charge VAT at 5 per cent instead of 20 per cent on renovating or altering an eligible dwelling that has not been lived in during the 2 years immediately before the work starts. Paragraph 8.3.2 sets out what proves the two years: Electoral Roll and Council Tax records, utilities companies, or an Empty Property Officer at the local authority, and states that a letter from an Empty Property Officer certifying two years empty is sufficient on its own with no other evidence needed. Paragraph 8.3.3 lists occupation that can be ignored: illegal occupation by squatters, occupation by guardians installed to deter squatters and vandals, and non-residential use such as business storage, but expressly not occasional use as a second home, which defeats the relief. Paragraph 8.3.4 allows the reduced rate to continue on all the work even where people move in while the work is carried out, provided the two-year test was met when work started. Goods that are not building materials, such as carpets or fitted bedroom furniture, must still be standard rated including the installation charge.
5technicalvery strongHM Revenue and Customs, guidance.RN-ZYLCD2The 5 per cent conversion rate and, importantly, what it does not cover. A qualifying conversion into single household dwellings arises where the premises after conversion contain a greater or lower number, but not fewer than one, of single household dwellings, and includes a property never lived in such as an office block or a barn, a bedsit block, non-self-contained living accommodation such as staff rooms above a pub, and a dwelling previously adapted in its entirety to another use such as offices or a dental practice. It expressly does not include the creation of living accommodation that is not a single household dwelling, naming most granny annexes and additional bedrooms at a care home, nor the renovation of living accommodation used for other purposes without adaptation, such as a flat above a shop used for storage, which is directed instead to the section 8 empty homes rate. Paragraph 7.3.1 makes clear that work unrelated to changing the number of dwellings cannot be reduced rated, and works three examples through a block of sixteen flats showing that parts of a building are examined independently. Goods that are not building materials, such as carpets or fitted bedroom furniture, remain standard rated along with their installation.