resource hub | Technical FAQs - Refurbishments & Conversions

Technical FAQs - Refurbishments & Conversions


As part of this month’s focus on refurbishments and conversions in our newsletter, our technical team have put together a few FAQs to help answer some of your questions. 


Q: Why do you need existing solid walls to be independently lined?


A: We don’t always, but most of the time yes, existing solid walls do need an independent lining, and some older cavity walls may also require similar treatment.


The reason being is that, in general solid walls provide opportunity for dampness and cold bridging. In addition, where a thermal element (a wall) is being renovated, if either 25% of the building envelope or 50% of the surface of the individual thermal element is being renovated it would be required that the thermal efficiency is upgraded and doing so reference should be made to other guidance elsewhere in the Regulations that would require consideration of moisture ingress.


There are scenarios for example. where a building has a listing, affecting the interior finish, or specific planning conditions where the above does not apply, however they are few and far between. In such circumstances we may have to consider whether we can provide warranty for these developments.


Q: Can existing solid ground floors be retained?


A: In general no. Unfortunately many existing concrete floors, flag floors and brick floors will not incorporate a damp proof membrane, and could be sat on excessive fill or have unacceptable undulations that would be unacceptable to a purchaser. Remember where a new floor is required you must consider the installation of insulation, which could provide further difficulties with levels


Q: Will I have to re-cover the roofs when converting my property?


A: In simple terms we can consider an existing covering and indeed always try to, however there are a lot of factors to consider, including local exposure, changing environment, general condition and original design. Most guidance documents suggest that slate roofs in excess of sixty years old will be approaching end of life in terms of fixings etc.


Some roofs of a steep pitch can be in better condition than those with a shallow pitch, however part of the reason behind including roofing felt below slates and tiles is not only to reduce capillary water ingress but also to reduce wind uplift.


The only way to determine whether the current roof covering is satisfactory and will in all likelihood perform for at least another 25 years is via assessment, in any case we would generally ask that the first metre of roofing is stripped from eaves upward as this is most likely where rot occurs but we can take a view, it is also useful to have a report from an experienced slater/roofer.


Telling signs such as all torching to the rear of slated roofs being on the current ceiling, slates/tiles routinely falling out and damp ingress would negate further consideration, but we would at least look and see whether we can consider. We would also need to consider whether the roof space is to be used for habitable accommodation.


More information:


If you would like more information about refurbishments & conversions or you have a question for our team, don’t hesitate to get in touch on 08444 120 888 or email


More information can be found in our Technical Manual