Most home units built in Australia will have a fire rating between each individual unit of up to four hours. To achieve this usually steel door jambs are used with solid brick or concrete walls. At the back of these steel jambs they usually will be filled with liquid concrete so as to minimise any air holes where heat could perhaps be concentrated. Usually, but not always, these jambs will have a rebate for the main door and a rebate for an additional door for security or insects. The main door will usually open inward and will be a very solid door that is purpose-built to allow security and the necessary fireproofing.
Double rebated steel jambs come in several variations and most of these will have 40mm opposing rebates, one for the main door and one for the security door or fly door. If this is the jamb that is installed at your door and you are wanting to install a security door or a fly door then you may have a problem as the doors will usually be only 20mm thick. In most cases the butt of the hinge will be out and therefore it would be more ideal to have this hinge butt to be external to the jamb to prevent squeaking noises and this may require the door to be built out. This can be done by using some form of beading whether that be timber or PVC. Beading is usually used on a door that has no rebate to provide a stop for the door and in the case of a jamb that is 40 mm thick can serve the purpose of allowing the door to be packed out so as to allow the doors to sit flush with the external part of the jamb. Most internal solid core doors will be around 35mm to 40mm and therefore no beading or packing is required. This is not the case if the jamb is 40mm thick and you require a 20mm security door to be fitted.
It is not impossible to fit a door up against the internal jamb, but can be problematic in two areas. Firstly, it will mean that you will have to have an extended striker so as to guide the lock into the locking hole. Secondly, it may cause the hinges to be noisy as they will be running up against steel and not protruding out to avoid rubbing as would be the case if the jamb had a 20mm rebate as is mostly the case with double rebated timber jambs. Also with a timber jamb it is quite easy to press the timber back or to chisel out a small piece behind the butt of the hinge to avoid a squeaking noise as the door is opened and closed.
When it comes time to install the door the main problem that will be encountered is the drilling of the holes for the hinges as well as the striker holes and this is amplified if a triple lock door is chosen. It is recommended that you use either 5/32 rivets or 3/16 rivets to anchor the hinges and the striker plates. This will depend on the weight of the door and the level of security required.
Once drilling has commenced and the outer steel is penetrated then the drill bit will immediately come in contact with some type of masonry whether that be brick or concrete and this has a dulling effect on the cutting edge of the drill bit. Unfortunately I know of no other way to initially hinge the door than to either resharpen the bit or use several bits during the process. Having said that there is a way of maximising the drilling process so as to avoid the need to resharpen or minimise the amount of sharpening required.
Once the door is hinged top and bottom and swinging freely and you have marked out your striker holes then a process called ribbon drilling is used to remove the steel from where the striker holes will be. Simply draw a square around this internal part of the striker plate and then using a sharp drill, drill marking points the entire outer perimeter at approximately 1mm apart. Without drilling right through, continue to drill each hole a little more stopping to move onto the next one prior to penetrating through to the masonry. If you are fortunate enough to remove 80 to 90% of the steel in the individual holes prior to penetrating through to the masonry behind then you will hopefully only use one sharp drill bit for this process.
If your drill has a masonry or hammer action on it then a worthwhile tip is to substitute your drill bit for a masonry drill bit at this very final stage. Now drill into the depth required. Once practised at this process it can definitely minimise the amount of sharp drill bits required; however, it does take some practice.
Good luck! And remember Seconline can fabricate Security Hinged Screen Doors to suit all jamb applications; contact us for a quote today or DIY and head direct to our website!