A Floors not being laid level is a common fault in house building. There are a couple of ways to solve the problem.

1) You can mix a sand and cement screed to bring the level up. This is a mixture of sharp sand and cement mixed at three parts sand to one part cement and slightly dampened. This can be laid at the lowest part of the floor back up towards the highest part. It is recommended that 50mm (2in) depth is required for screed. However, I would say it is possible to use it to a depth of 37mm (1.5in). Any lower than this and the screed will ravel away in time. Then you need to use a levelling compound to make up the rest of the levels. It is better to use floor-tile adhesive mixed to a creamy consistency to bring up the level as it has a stronger substance than levelling compound. Levelling compound is really only to be used to make up minor discrepancies in floor levels.

2) It should be possible to fix battens to the floor and then fit plywood onto these. The battens will have to reduce in thickness as you get towards the high point of the floor. When it is no longer suitable to use battens . . . ie when the thickness is only that of the ply . . . that is your stopping point and you then use floor levelling compound/floortile adhesive to level the remainder of the floor. Be careful when fixing the battens that there are no pipes or cables, etc hidden in the floor.

Compression anchors are the best way to secure the battens.

Q I am dividing a large house into two apartments. What do I need to look out for?

Dublin reader

A Look out for your local planning office! That should be your first port of call. Bring a rough design of your house or if you have the original drawings all the better. You will need to also roughly sketch what you are proposing to do. The planning office will advise you as to the procedures required to secure planning permission for this and it would be advisable to engage an architect to draw up detailed plans based on the planner's advice. You will need to have independent electricity and water supplies into both apartments. Is the house connected to mains sewerage or septic tank? If it is a septic tank then you will almost definitely need an independent tank for each apartment. You also need to look out for fire-safety measures. Soundproofing will also be a big factor to consider. If you engage a good architect he will draw up the plans to cover everything required for building regulations.

Q I have a manhole which keeps blocking up and which I have to rod frequently. How can I find out what the problem is?

A If the house is relatively new then I am almost certain the pipes have not been laid properly. By this I mean that the incorrect material has been used underneath the pipes to provide a solid bed for them to lie on. I have seen people laying the pipes onto the bare earth. This is not a good idea as the earth moves and settles and inevitably causes humps and hollows in the pipes which then cause the blockages to build up. The sewer pipes should be laid on a 150mm (6in) bed of pea gravel around 10mm deep. This will give a solid bed for the pipes and can be levelled sufficiently by removing high spots or filling low points.

It is possible to employ the services of an underground CCTV company who will be able to identify the problem 100% and show you on camera. This will also help in the fact that you only need to dig up and repair the sections that are causing the problems.

Can you tell me why some push-fit plumbing fittings have a different colour plastic ring around them? I saw them in a DIY store and asked the assistants but no one seemed to know the reason.

D Delaney The reason there are green sleeves and brown sleeves is that the green ones are for the Irish fittings and the brown are for imperial fittings. It is a nightmare if you use the wrong fittings as they will most definitely leak.

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If you have a building-/renovation-related query that you'd like Steve to help you with, email: doorstepdoctor@tribune. ie Steve Guerin is managing director of www. tradesmenireland. com, the one-stop website that will help you find a tradesman, a site for sale, a property to rent or buy and all the plant hire and machinery you need to complete your house build or renovation