Ask the Experts Grand Designs Q&A: July '09

Date Published:

04/06/2009

Install a Green Roof

I have a flat-roof extension and would like to update the traditional roof covering in favour of an environmentally friendly green roof variety. Will the current structure be able to support the extra weight?

Stuart Tappin says There are two types of green roofs, referred to as intensive or extensive. An intensive roof has plants sitting on a thick layer of soil above a drainage layer. Typically, the soil is about 450mm thick so that the planting follows that of a normal garden on the ground. This thickness of soil is quite heavy, so it’s unlikely your current roof will be able to support this. The alternative is an extensive roof, which has a thin, lightweight layer of free-draining material that supports low-growing, drought-resistant vegetation which requires little maintenance. The total weight of this type of green roof can be as little as 100kg per sqm. Most roofs have a certain amount of ‘spare capacity’, but you will need a structural engineer to check the size of the existing roof members to see whether it can support this additional load. Find a local structural engineer at the Institution of Structural Engineers’ website (istructe.org).

My build costs have increased since I started my project, and I now need to find extra finance to finish it. What are my best options?

Mary Riley says This can be quite tricky. A lot depends on the stage you reached on your project prior to running out of cash, and also your affordability to raise more capital to complete the build.

First, arrange a meeting with your existing bank or building society as they will need to know why you went over budget. If your current lender is comfortable with your rationale and you still meet lending criteria, generally, they will consider lending additional funding, which will normally be in the form of a further advance. You will certainly incur additional lender and valuation fees, and the rate of interest will more than likely be different from the deal you have already secured with them.

If you applied for funding via a mortgage intermediary, they may also charge you a fee to arrange the additional borrowing. This may seem harsh, but in order to comply with the Financial Services Authority (FSA), if your original fact-find document is more than six months old it is a requirement that you are treated as a new client. Basically, everything starts from scratch – new fact find, initial disclosure document, etc – as any lending approved must be affordable and responsible.

If your current bank or building society is uncomfortable to lend, or will not release the additional funds you require until the end of the build project, you may be in a position to remortgage your current mortgage facility to a new lending institution. The level of funding approved must again meet lending criteria. However, subject to current loan to value, you may be able to access additional funding at an earlier stage than your current lender was prepared to lend, and you may also have a wider choice of mortgage products. Some banks and building societies lend initially to purchase land (minimum of outline planning permission in place), others lend after the foundations are in place, built to eaves height (just before the roof trusses go on), or at wind and watertight/roof tiled stage of the build. It is best to engage with specialist mortgage companies, as being credit checked too often can have an adverse effect on your credit rating. Check out Buildstore (buildstore.co.uk) or Self-builder.com who will be more than happy to discuss your funding requirements and advise accordingly.

While I can understand how important it is to finish your project, I strongly suggest that you do not borrow additional funds on credit cards. This is a very expensive exercise and could lead to problems in the future, particularly if this means that subsequently you are overstretching your affordability to meet your current and new financial commitments.

A final option, which could be the best route if you are nearing the completion of the build, is to speak to your suppliers and ask them if they will consider extending your payment terms. It may be that once the build is complete and you have obtained your completion certificate, you will be able to remortgage to another provider. This may be an option as you ought not to be high loan to value and, as you know, more banks and building societies lend on fully completed houses rather than self-build projects. Good luck.

This edition of Ask The Experts is taken from the July issue of Grand Designs magazine. If you would like to subscribe for as little as £9 then head here to find out more.