The project is to convert the remaining loft space, adjacent to a 4th floor loft conversion apartment situated within the roof space in a 1930,s traditional 3 floored detached house. Although the free space to be converted is small (approx. 6 square meters) and the roof angle virtually cuts the total volume in half, effectively cutting out nearly 50 percent of the floor space if to be used by adults (head height reduced by roof slope). It could be a practical kid’s bedroom space owing to children needing less room height and the very low area could be employed as a practical storage space for toys etc.


The entrance door leads from the bathroom of the existing apartment, there is sufficient space within the bathroom to partition a corridor from the new room to the main living area, effectively bypassing the existing bathroom for practical reasons. The existing central heating system consists of a gas combination boiler which is conveniently situated adjacent to the proposed bedroom, simplifying the work involved with the extension to the central heating circuit (of course, the capacity of the existing central heating system should be quantified before any work commences to check that it is capable of coping with the extra radiator. Due to the new space being a bedroom, unlike a kitchen the expected electricity load will be minimal so a spur (electricity line) can be taken from an existing circuit on the system. It is not necessary to create a dedicated circuit from the main consumer unit with its own dedicated trip switch.



The most important thing to establish is the structural stability of the existing structure. Because any work carried out within a previously uninhabited structure will cause new loads, stresses & vibration, it is vitally important to determine the structural stability and hence, the ability of the existing structure to cope with not only the proposed final purpose, but also the stresses caused during the work.
There a many factors that will effect this ability, old structures move over time and eventually settle into equilibrium, the stability is finely balanced, structural beams and columns weaken with time, not just age but other factors such as dry/wet rot, fungal and insect infestation, degradation of metallic fixings (nails/screws etc.). A thorough inspection must be undertaken by a qualified professional.
 I am a UK degree qualified building engineer and from my 20 years of experience I can tell many 'horror' stories of situations where this first 'professional inspection' has been overlooked, leading to not just large financial loss but also danger to life (it’s a long fall from the second or third floor) if you don’t establish a safe working environment to start with.

For a thorough inspection to be undertaken, it is necessary to remove anything that covers important parts of the structure, this includes old insulation, wallpaper, floorboards etc. so that any hidden problems can be confronted.
 
 With this loft space there was very little evidence of dry/wet rot or fungus because the structure was waterproof and well ventilated, there was however an infestation of wood boring beetles {woodworm)

Because of the woodworm infestation, it was necessary to remove all the existing coverings to the structural timber in order to expose all the infected areas.
The type of woodworm was identified as the Common Furniture Beetle (Anobium punctatum). In most cases treatment of Common Furniture Beetle is fairly straightforward. Any structurally-weakened timber should be removed and replaced with pre-treated timber. All surfaces of the affected timber should then be treated with Woodworm Treatment applied by brush or spray.
    

 

 All the infected timber was cut out, first ensuring that the remaining ‘good’ timber would be of adequate size and strength to perform its intended structural purpose. The depth of infection was up to 25mm in the worst areas, leading to the requirement for one of the vertical columns to be reinforced before the bad wood was removed and remaining good wood then treated.
As can be seen in the following photographs,the worst infected wood was removed gently by scraping it away, the remaining good wood  was then reinforced with two (60mm by 150mm) pine columns that had been pre-treated againt woodworm. Thes were attatched securely to either side od the existing column, with numerous steel bolts, penetrating completely through the ‘heart’ of the good remaining timber, effectively joining all the timber together to act as one structural column. This provided adequate support to the beam resting above before the remaining infected timber could be removed and the remaining good timber treated.


    
    
  There are many solutions available for treating woodworm but the basic application method is as follows. Firstly however, it must be understood that these chemicals are harmful to health and sufficient protection must be provided against inhalation and contact with the skin. The financial cost of this protective equipment makes it impractical for use on a single job. It is more economical to employ a specialist to do the job, you get the advantage of a warranty if the treatment is unsuccessful and also avoid risk to your health from what is not a ‘pleasant’ job.

         
      8mm diameter holes are drilled in and around the infected areas, vertically in beams and as close as possible to vertical in columns, to a depth of about 40-50mm, approximately 100mm apart. The solution was prepared according to the manufacturers instruction and poured in the holes. The total surface area of the infected wood was thoroughly sprayed with the solution. The work is then stopped until the solution has had time to do its job, according to the manufacturers instructions.

During the life of the building, various parts of the structural timber have become damaged or removed for various regions. Where replacement is not possible for practical reasons, if structural stability remains adequate, then reinforcement is added to prevent further damage.

  
   As shown in the above photographs, splits in vertical timbers are prevented from getting worse by clamping them together with the aid of metal bolts (ringed in red on photograph). Other damaged areas are repaired with fresh timber, pretreated against woodworm.


As The entire roof covering was replaced only six months before with metal roofing cladding and lined beneath with moisture proof paper, there is no evidence of damp on the underside even though there has been much rain since, so it is safe to assume that it is weatherproof and work to insulate the underside can proceed.
However, as can be seen from the photographs below, daylight can be seen through gaps in the external cladding of the external wall. This wall is exposed so its resistance to the wind and rain needs to be improved before the insulation can be installed.

                    

Moisture proof paper was applied to the wall, with any joins overlapped and taped. Boards were then fixed over the gaps in the external cladding.

               

Wind resistant board was then secured over the top and any remaining gaps were sealed with a foam filler that is suitable to withstand freezing temperatures because it is located on the outside of where the insulation will be placed.

          
  

Two layers of mm thick insulation matting were then applied to the wall, supported with a string harness so as to prevent them from slipping out of position and leaving gaps. The string used was synthetic so as not to rot and break over time, letting the matting slip.

         

    
 
The same system was used to insulate the ceiling under the new roof covering, creating a completely weather proof, insulated external shell to the new bedroom. As the area below the floor is an occupied space and heat travels upwards, it is pointless to insulate against heat loss.

            
      


When the interior had effectively been protected against water leaks and dramatic changes in temperature and humidity, the new floor could be started.  The existing beams (third floor ceiling/attic floor)were found to be of sufficient size and adequate condition to support the proposed floor structure for the new bedroom, consisting of pine interlocking floorboards, resting on pine floor support beams. These floor support beams were supported off the existing attic floor structure and fixed securely as indicated in the photographs below. These floor support beams provide two functions. They effectively raise the finished floor level to match the level of the floor in the existing attic accommodation, it also provides  the space under the new floor, allowing ventilation which will reduce the chances of problems like rotting and fungus.

Floorboards were then selected of adequate length and thickness to span the gaps between the floor beams and not result in any of the board ends being unsupported at a joint by a support beam, resulting in a finished floor being of sufficient strength and stability for its purpose. The boards were then laid with the joints staggered to form a uniform pattern.

 
It is important to store the boards in a place of similar humidity and temperature to where they are going to be fitted, for some time. This is because they are usually stored outside at the suppliers, if they are fitted straight away, they can shrink or expand because the moisture content will change. This will result in buckling or gaps between the boards in the finished floor.


Because the opposite walls were not parallel, as is normally the case, it is important to start from the center of the room and work out towards the edges, this results in the difference being minimized when the floor is completed. If you start from one side, the difference will be very obvious by the time you get to the other side. The boards are nailed through above the tongue at a 45 degree angle and punched home with a nail punch. The boards then slot together smoothly and are hidden from view in the finished floor. The last boards are then cut to fit 5mm from the walls to allow for any expansion. This gap will be hidden when the skirting boards are fitted to the bottom of the walls.

 


6mm particle board was chosen in favor of plasterboard because of its strength for supporting shelves and other fittings. This was cut to the correct size and screwed to the ceiling joists and structural beams & columns on the walls. All edges of the boards require fixing so additional timber was added where required, attached to the structural supports.

          

      
 
A support frame for the boarding was fitted around the ‘Velux’ window, making sure that all voids were filled with insulation wool.

        
   
The gaps where the boards join were then filled with flexible filler and the surface of the walls and ceiling smoothed and prepared to receive a decorative paint finish.

       
    

The walls & ceiling were then painted with one coat of base paint and two coats of top coat. The exposed woodwork was then given a final sanding and given a finish of linseed oil.


The floor, left until last was then sanded smooth, the gaps between the floorboards and central beam were filled with flexible parquet filler and then finished with linseed oil.

        

 
Finally, the bedroom was wired up for lighting and a radiator fitted with pipework connected to the existing system.