Hullo Masklin, it does sound like a tricky situation, and I'm sorry to hear about these additional costs. Building work is always expensive to begin with, and additional and unexpected costs are never welcome. In respect of whether there is scope to obtain costs for this from your architect and structural engineer, this will most likely come down to the original appointment, their scope of involvement in the project, and whether they where direct appointments with you - or whether the SE was appointed through the architect. If the architect and SE were appointed to undertake planning and building regulations drawings with no exploratory or invasive works (ie stripping back existing structure in the house to assess structure before the project was tendered) then there will have been a number of reasonable assumptions on their part, which will only have been assessed when a main contractor started. The conversion of the attic would have added some additional loading to the property, but certainly less than adding a whole additional storey. There is every chance that additional bedroom space at this level would have less weight implication than someone stuffing their attic full with storage. SE's are notoriously cautious, so their assumption for the attic should have taken into account any additional loading, and if an existing (previously completed) opening needs to be reinforced, it might suggest that the existing opening was not designed appropriately to begin with. The flaws in existing structural design would generally fall into 'unforeseen' items, which is generally where contingency funds are intended for use. However, as others have suggested, if you are unhappy you can always pursue this further through the ARB, or RIBA (if your architect is a member of these bodies) or through the body that the structural engineer belongs too - but it is always worthwhile starting a discussion with the architect and SE and asking them to clarify how this happened. They will no doubt want to try and address this and have the opportunity to resolve this with you direct. Check your appointments with them, and what they were briefed (and paid) to undertake on your behalf. It might also be worthwhile trying to source any information you can about the original works and structural beam that got installed. Hopefully there will be a positive outcome from it all. Good luck! K :)

I think the plan looks more like this?? Therefore, the plumbing is at the rear of the house as you'd expect. Thus the kitchen needs to be near that. So, i'm guessing that you may have room by the stairs for a little window or possibly a light tunnel. As you say the back garden is level to that floor, i'd put in french doors for extra light at the rear. I would not knock down the wall between the dining room and the corridor as, with the kitchen the other side of the rear, you will have no view of it from the relaxing area behind the dining room table - I would also retain around 500-600mm of the wall between the kitchen and the dining room so that a structural steel can sit above it without ( hopefully ) the need for underpinning or a party wall agreement. - ALWAYS CHECK! Thus, it could look something like this:-

Hi Sarah, Almost any floor covering can work well with underfloor heating. Each floor covering will provide a different level of thermal conductivity, making it easier or harder for your underfloor heating to meet the desired floor surface temperature. It's a good idea to choose an underfloor heating system that has been designed with your choice of floor covering in mind, as this will provide the most efficient heating for your home, as well as ensuring that sensitive floor coverings are protected. Engineered wood is an excellent choice for pairing with underfloor heating, as it is effective in transferring heat from the underfloor heating tube to the surface of the floor. It can also generally be laid directly over the underfloor heating without the need for an additional, structural floor deck - your underfloor heating supplier will be able to advise if this is the case. We would always recommend that you ask your flooring supplier if there are any special care conditions (such as maximum temperatures) for your flooring. If needed, your underfloor heating supplier should be able to provide a floor temperature sensor which limits the heat output from the floor to protect the floor coverings, whilst still ensuring that the desired room temperature is met. We will be more than happy to answer any questions you might have about pairing floor coverings with underfloor heating. Please feel free to give us a call on 01404 540650 if we can be of any help.

Has anyone bought an additional structural warranty insurance over and above the normal householder insurance which is taken out when you undertake a big builder project? I know I may have to pay an additional premium for my buildings and contents insurance. I have read about longer term insurance which will stay in place once the work is completed. We have an architect, a structural engineer and building control on board and will get all the required certificates and the works signed off. Thanks in advance!