Mixed Construction Waste in Skips: EWC Codes Guide

A skip on a building job rarely contains one material. By the end of a week it holds plasterboard offcuts, bricks, timber, a few paint tins, some pipe lagging and whatever else the site team threw in when nobody was looking. For a skip hire firm, that mixed load is the normal product. The paperwork question is what code and which note describes it, and the commercial question is what happens when one wrong item turns the whole load into hazardous waste.

This guide covers how mixed construction and demolition waste is coded, the items that most often cause contamination problems, and what skip firms and their customers can do to keep loads classified correctly. It applies to England and Wales in the main, with notes on Scotland and Northern Ireland where the position differs.

What counts as mixed construction waste

Construction and demolition waste sits in chapter 17 of the List of Wastes (the EWC codes). Where a skip contains several different materials that have not been separated, the usual entry is 17 09 04: mixed construction and demolition wastes other than those mentioned in 17 09 01, 17 09 02 and 17 09 03. It is a non-hazardous code, and it is the one most skip hire firms will see on their notes every day.

Two neighbouring codes matter just as much:

• 17 09 03*: other construction and demolition wastes (including mixed construction and demolition wastes) containing hazardous substances. The asterisk means it is a hazardous entry and needs a consignment note, not a waste transfer note.
• 17 01 07: mixtures of concrete, bricks, tiles and ceramics. This is for a mostly inert load, not a general mixed skip, and it usually goes to a different destination and often a different gate fee.

Single-material loads should use their own codes where they can: clean timber (17 02 01), mixed metals (17 04 07), gypsum-based materials (17 08 02) and soil and stones (17 05 04) are all examples. Using 17 09 04 for a skip that is, say, 90 per cent clean timber is not wrong in itself, but it can mean your customer pays more than they need to and your site cannot send the load for recycling. The first two digits of an EWC code give the chapter and the next two the sub-chapter, so 17 09 sits within construction and demolition waste.

How classification works for a mixed load

The government's technical guidance on classifying waste, known as WM3, sets out the method. For a mixed load, the rough logic is this: identify what is in the skip, check whether any component is a hazardous entry in its own right (an absolute hazardous entry such as asbestos), and where an item could be either hazardous or non-hazardous depending on its content (a mirror entry) assess it against the hazardous properties. If hazardous items are present in the load, the whole load can no longer be described as non-hazardous.

That is the point where a tidy 17 09 04 skip becomes a 17 09 03* problem. The Hazardous Waste Regulations also restrict mixing hazardous waste with non-hazardous waste unless an environmental permit allows it. If a contractor drops a quantity of hazardous material into a non-hazardous skip, the loader has not just made a classification error; the mixing may itself be a breach.

You do not need to run a laboratory analysis on every skip. WM3 expects a reasonable, proportionate assessment based on knowledge of the waste and its source. A kitchen strip-out in a 2015 house and a demolition of a 1960s school are very different starting points, and your questions to the customer should reflect that.

Items that most often contaminate a skip

These are the items skip firms and waste transfer stations tell us cause the most trouble. Always check the current classification of any specific product against WM3 and the safety data sheet.

Asbestos-containing materials

Asbestos is an absolute hazardous entry (17 06 05*). Any building built or refurbished before 2000 may contain it: cement sheet roofing, soffits, floor tiles, textured coatings, pipe lagging, fire doors and insulation boards among others. It must never be placed in a general skip. If a customer suspects an item contains asbestos, stop, do not break it, and see our guide to asbestos waste disposal. Asbestos found in a mixed load at a transfer station can lead to the whole load being rejected and to a report to the regulator.

Paint, adhesives, sealants and solvents

Part-used tins of solvent-based paint, tile adhesive, mastic and sealant often contain hazardous substances. Water-based paint is generally treated as non-hazardous, but a skip full of mixed tins is hard to sort once the lids are off and the contents have leaked into other waste. Tell customers to keep tins sealed and out of the skip altogether.

Treated and contaminated timber

Most clean construction timber is non-hazardous. Wood treated with creosote, or old timber from industrial or railway settings, may be hazardous. Heavily painted older timber is a judgement call: the age of the building and the likelihood of lead-based paint matter. Where you are unsure, ask what the timber was used for.

Plasterboard and gypsum

Plasterboard is not hazardous, but it causes problems of its own. Landfill rules restrict gypsum from going into cells that take biodegradable waste because of the risk of hydrogen sulphide. Many sites ask for it to be kept separate, which is why a plasterboard skip is a better answer than a mixed one. Our article on plasterboard and gypsum waste covers this in more detail.

Insulation, fluorescent tubes, batteries and electrical items

Some insulation materials are non-hazardous (17 06 04), but others, particularly older products, are not. Fluorescent tubes contain mercury and are hazardous, as are lead-acid batteries and some other battery chemistries. Electrical and electronic equipment is a separate stream under the WEEE rules. None of these belong in a mixed skip.

Soil and stones from unknown ground

Soil is not automatically inert. Made ground, former industrial land and fill of unknown origin can be contaminated. If a customer is putting a pile of soil into a mixed skip, that changes the code and may change the destination.

Before the skip goes out

Most contamination is prevented at the point of booking and delivery. Practical steps that cost little:

• Ask what the work is. A bathroom refit, a roof strip, a garage clearance and a shopfit have different risk profiles. Record the answer on the booking.
• Ask about the age of the building. Anything pre-2000 prompts a question about asbestos. If the customer does not know, tell them how to find out and what to do if they find suspect material.
• Give a clear banned-items list. A printed or texted list of items that must not go in the skip (paint, solvents, tubes, batteries, gas bottles, asbestos, electrical items, tyres) is far more effective than a verbal reminder.
• Offer separate containers where it makes sense. A small plasterboard skip or a bag for hazardous items can be cheaper for the customer than a downgraded mixed load.
• Photograph the skip on delivery and on collection. A dated photo of the load as it left site is useful evidence if the contents are later disputed.

Checking at collection

The driver is the last person who sees the skip before it is tipped. A quick walk-around is part of your duty of care. Look for tins, pipe lagging or sheet material that looks like fibre cement, bags that might hold something other than rubble, and anything with a hazard label. If you find something, do not load it. Photograph it, note it on the job, and tell the customer in writing what you found and what has to happen next.

If the load is only partly contaminated, you have a choice: remove the item and carry on, or reclassify the load. Removing a single tin and leaving it with the customer is reasonable for a minor item; leaving a customer with a suspected asbestos sheet is not, and you should explain they need a competent contractor. Never carry on with a load you believe contains hazardous material under a non-hazardous code.

The paperwork: description, code and note

For a non-hazardous mixed load, your waste transfer note should carry a specific description, not just the words "mixed waste". Something like "mixed construction and demolition waste from kitchen strip-out: brick, plaster, timber, ceramics, plastics" tells the next person in the chain what they are receiving. The code is 17 09 04 for most mixed skips. Our article on writing a good waste description has examples that hold up when an inspector reads them.

A WTN must also include the other particulars required by the Duty of Care Regulations, including the quantity, the container type, the parties and the place and time of transfer. Where hazardous items are present and have been separated into their own container, that container needs a consignment note and a hazardous code, while the remaining skip can still use a WTN. The two documents cover separate streams; you cannot put hazardous waste on a WTN. Our guide to waste transfer notes versus consignment notes explains the difference.

If you are using the free note creator at qwtn.co.uk/notes/new, pick the code and description that matches what is actually in the skip, and add a line about the property and the work. Time spent here pays back when a note is queried two years later.

Keeping evidence and rechecking your process

If an inspector or a customer questions a load, what protects you is a trail: the booking, the answers the customer gave about the building, the delivery and collection photos, the note and the transfer station weighbridge ticket. Keep them together under the job reference, for at least the minimum retention period (two years for a WTN, three for a consignment note).

Review your process every few months. Look at which jobs gave you rejected or downgraded loads and what they had in common. Often the answer is a customer type (a particular trade, a landlord clearing property) or a type of job (loft conversions, older commercial refits), and a small change to the booking questions or the banned-items list fixes it.

Scotland and Northern Ireland

Mixed construction waste is coded in the same way across the UK because the List of Wastes underpins all four nations' systems. Hazardous waste documentation, producer registration and some of the detail differ. In Scotland, SEPA publishes its own guidance, and in Northern Ireland the NIEA does. In Wales, Natural Resources Wales regulates. If you work across borders, check each regulator's current guidance rather than assuming the English rules apply. The hazardous waste rules in particular are worth checking before you take a job across a border.