Leslie O'Donnell
Building or extending a house generates a lot of waste, in the form of solids, liquids or sludges, all of which will cost money to dispose of. The first step therefore is to design waste out of your construction drawings, writes structural engineer and architectural designer Les O’Donnell.
Whose job is it to dispose of the waste your house construction creates on site? The polluter pays principle applies, i.e. it is ultimately your responsibility.
This usually means segregating between what can be reused on site, what can be recycled off site and what needs to go to landfill. Organise the waste destined for landfill or the recycling facility so that it can be placed in the relevant containers.
Refuse and reduce
You can refuse any unnecessary packaging by telling suppliers that you don’t want it, or ask them to take it back with them after delivery. Make this clear when placing your order.
From the beginning, try to work out how much waste you might end up with, by looking at the design and making sure it works to standard dimensions. If in doubt, allow 5 per cent of all materials being subject to cutting, trimming or adjusting. Over time, this will add up to a big pile.
Know that plasterers, tilers and so forth will have leftover material to discard, and they won’t want to take it away with them. If you are hiring a main contractor, waste management should be included in the contract. If waste can be designed out of your plans, you will expend much less effort and cost in dealing with what remains. Helpful tips to reduce waste include:
- Keep the design layout simple and use standard dimensions to avoid excessive cutting of materials, e.g. wall areas, room sizes and ceiling heights should match standard brick, block and panel dimensions. Offsite or Modern Methods of Construction can reduce significant amounts of site waste because all parts that arrive on site are used.
- Keep an eye on the tendency to over engineer some structural items; oversized beams, columns, slabs, etc. contain material which is unnecessary and technically therefore, is waste.
- Overordering or ordering too soon can result in materials or products stored on site becoming damaged and unable to be reused. A good weather-tight storage facility is very useful which is why many selfbuilders build their garage or shed first.
- Consider that a building designed to suit the site contours will reduce excavation and fill operations.
- Find out the lifespan of each building component and how and when it will need to be maintained, repaired or replaced. Anything going into spaces which are to be permanently covered should have a lifespan equivalent to that of the building.
Reuse, recycle and recover
A lot of what is commonly regarded as waste does not need to be dumped – in fact, landfill should only be the last option. Easiest to deal with are bits of unusable metal which can be sold as scrap, but wiring, straps, sheet materials and pieces of plasterboard will usually end up in landfill. That said, lengths of discarded pipe can be used for underfloor ventilation.
Dry untreated natural timber offcuts can be used as fuel in your new wood-burning stove but other types of timber need to be disposed of. Treated timber is considered hazardous waste. The other main categories of discarded items include:
Insert material If there are buildings to be demolished it could be worthwhile to hire a crusher to produce aggregate directly from old unreinforced concrete, bricks and blocks, etc. Defective bricks, blocks, slates, tiles or pavers can all be broken up to use as inert fill material or as filter media in the bottom of surface water soakaways. Offcuts from reinforced concrete lintels can be used as pad-stones under steel beams but check with your structural engineer.
Plastic Look for the recycling logo on hard plastic (most can be recycled). As a rule of thumb most packaging, e.g. film like plastics and styrofoam, aren’t recyclable. Chunks of plastic based insulation material can be fitted into gaps to enhance the thermal efficiency of your dwelling, although in reality many insulation products can’t be recycled and most of the offcuts will be skipped.
Skip hire
Having taken every opportunity to reduce and reuse waste materials, the next step is to deal with what is left. It is important to get advice on dealing with construction waste from your local council, which may also have a scheme for leaving a skip on your site.
Private skips for hire will usually have a cheaper price for inert material only, but most people opt for mixed skips which includes everything from plasterboard to plastic. According to EnviroWise UK the true cost of a mixed construction waste skip is over 15 times the cost of the skip hire due to sorting.
Currently, the typical cost of hiring a medium sized skip (7-8 tonne) is around £120.00 + VAT in NI / €300 in ROI. Larger skips reduce the cost of disposal per tonne. Bear in mind that skip filling needs supervision to avoid creating more waste than you expected (know what you will be filling it with as a priority), and if placed along a road make sure it is securely covered so passers-by don’t use it for fly tipping. Most operators also require that you do not overfill it (must be level with the top of the skip).
Trips to landfill
The alternative to ordering skips is to make trips with your van or trailer to the local council waste facility, where they will charge for anything that is neither household waste nor recyclable.
If transporting your own waste, get a list from your council which shows the categories of waste and how much it will charge to process them.
In ROI you will need to register with the local council to get access to the landfill; the weight of your car and trailer or van is weighed upon entering and exiting. The cost varies but there is usually a minimum charge plus €200 per tonne. The costs in NI tend to be lower with local authorities charging by type of waste. Charges at a typical council waste facility, which may differ in certain areas, are plasterboard at £50/tonne, timber at £41/tonne and contaminated soil at £30.50/tonne.
A back of the envelope calculation comparing trips to landfill versus skip hire weighs heavily in favour of making the trips, even if you hire casual labour to do it for you. Check in advance that the landfill accepts construction waste.
In the dumps
If not using a council skip or making trips to landfill, you must make sure that whoever takes it off your site is authorised to do so. Only give waste to local council waste services, a council-authorised waste contractor, licensed private waste operator or registered waste carrier.
There have been reports in the media recently of individuals posing as waste contractors, who charge a low fee and dump the waste illegally. If the price is too good to be true, there is usually a reason.
Be mindful too that if left unsupervised, the old practices of burying waste, incorporating unsuitable materials in fill and chucking cast-off items into cavities, voids and drainage trenches, will still happen.
A site which is kept clean and tidy on a daily basis, with unused materials stacked neatly, is always a good indicator of your workers’ attitudes to waste. If you are managing the site make sure you keep it clean, as this should help others on site be tidy too.
Hazardous waste
Brownfield sites are defined as containing contaminated soil, but even a greenfield site can contain buried waste, so if you identify anything that looks like hazardous waste*, you must obtain expert advice on how to deal with it. The penalties for failing to control hazardous waste are severe.
The other source of hazardous waste for self-builders tends to be found in demolition works, due mainly to the absence of past legislation. Asbestos is a hazardous material that can be found in roof, ceiling and floor tiles, slates, some plasters, insulation and vermiculite products, and the cost of removal can easily run in the thousands.
Generally speaking, do not mix hazardous wastes with each other or with other non-hazardous waste, supervise what your site workers are dumping into the skip or trailer and prevent access to the skip by any unauthorised persons
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