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Building a House


Different building methods and materials

As briefly discussed under the heading National Building Regulations, a prospective home owner or designer is actually encouraged by the Regulations to use innovative designs and alternative building materials. The promulgation of this Act therefore saw the spawning of an extended series of alternative building materials, including timber products and quite a lot of different pre-fabricated systems.

Since the detailed discussion of all these different innovative or alternative building methods is way beyond the scope of this website, inhouseplans.com focuses solely on building plans for houses built from old fashioned, trusted (and economical) bricks and mortar. It is however possible to use alternative building materials (especially timber) for a house, based on one of the provided building plans.

Site cleaning and stripping

Before any foundation excavations are undertaken the site must be properly prepared and cleared by removing all rubble and plant material like grass and shrubs. If the site is saturated by ground water, or if the natural flow of rain water is across the site, a proper drainage system must be provided to drain the water to the municipal storm water system. Care is also required not to generate unnecessary dust and noise pollution.

Anybody building a house is allowed to erect a temporary builder's shed on the stand, but he/she is obliged to provide the necessary sanitary facilities for the workers on the site. One facility per 30 workers must be provided.

Bulk earthworks and excavations

The owner must ensure that all earthworks and excavations are safe and stable. All excavations deeper than 3 m must be designed by a competent person, and must be approval by the local authority.

All excavations for strip foundations must be level (horizontal). Where an excavation goes across a slope in the land, it must be stepped into horizontal sections.

All excavations for strip foundations must be at least 300 mm deep.

The bricklayer is the person responsible to mark out on the ground the position of the house, including all outer and inner walls. This is usually done by using a tape measure and physically marking the outer dimensions of the foundations on the ground using dry cement powder. Since it is much easier to move a line on the ground than to move a finished wall, the owner should ensure at this stage that he/she is satisfied with the position of everything.

It might even be advisable at this stage to appoint a surveyor to confirm that everything has been set out correctly. This may save enormous cost later when for instance an encroachment of a building line has occurred.

On completion of all foundation excavations, and before any concrete is placed, the building inspector of the local authority must be called out for a compulsory foundation inspection. During this inspection the dimensions and level of the excavations will be scrutinised, and it will also be ascertained whether the builder has deviated from the approved building plan, and whether the layout is positioned as indicated on the plan.

Foundations

The foundation of a building must be designed in such a way that it could easily transfer the weight of the wall and roof to the ground. In order to achieve this functional regulation, the deemed-to-satisfy rules include the following:

Concrete mixed to be poured into the excavation must produce a strength of at least 10 MPa after 28 days. This is obtained by mixing 1 part cement, 4 parts sand and 5 parts aggregate (usually 19mm stone). The thickness of the foundation must be at least 200 mm, and when a step is formed, the top layer must overlap the bottom layer with 200 mm (the thickness of the layer). The width of the foundation strip must be at least 600 mm for load-bearing (usually all outer) walls, and 400 mm for non-load bearing (usually all inner walls). In the case of non-load bearing inner walls, it is also permissible to provide a thickening in the floor slab instead of an own foundation strip. If this option is preferred, the thickening in the floor slab should be 200 mm.

In the case of suspect ground conditions, inhouseplans.com strongly recommends that a civil engineer be approached to recommend a specific design for the foundations.

Building of foundation walls

A foundation wall is that wall built on top of the concrete foundation strip, to the height of the floor slab. All foundation walls must be 220mm (two bricks) wide. If a foundation wall is going to be higher than 1,5m, the house should be stepped to accommodate the slope of the land. If such a foundation wall is also used as a retaining wall, it is advisable to build it 330mm (3 bricks) wide. Foundation walls of higher than 1 m should be reinforced with brickforce every second layer, as well as when clay condition occur.

Backfill of foundation walls and damp proofing

Once the foundation walls have been built to floor level (also called the "plinth"), the inside of the house must be filled up (backfilled) to floor level. It is usually possible to use the same material that was excavated for the foundation strips, so always try to leave this material close by. In order to prevent sagging under the floors, it is important to compact this backfilled material to closely resemble the natural density before excavation. This is easily accomplished by replacing the filling in layers of 150mm, compacting each layer properly with a mechanical or hand compactor. This process will be improved if the layers are sprayed with water to dampen it. Always take care however, not to totally soak the material, as this will wash out all the fine material that is supposed to fill the smaller openings.

Continue with the backfilling until the final level is one brick below the final floor level, which will also be the thickness of the concrete floor bed. Try to make this top layer as level as possible. When ground condition are suspect, it may be advisable to consult a structural engineer, because a mesh of steel reinforcement may be required.

Pouring of floor slabs

The concrete floor slab must be 75 mm thick (one brick layer) and consist of 10 MPa concrete, mixed from 1 part cement, 4 parts sand and 5 parts 19 mm aggregate. In areas where groundwater is a problem, it is advisable to place a suitable plastic water proofing membrane of 0.25 mm on the filling prior to pouring the concrete. This membrane must, around the perimeter, be folded upwards to the thickness of the concrete. An overlap in the membrane must be at least 150 mm.

It is advisable at this point in time, to consult with your plumber and electrician to ascertain whether any services like electrical conduiting pipes or drainage pipes must be placed in position before any concrete is poured. This will eliminate later chiselling and breaking out of the concrete and disturbing the compacted fill bed..

Brick walls

On completion of the concrete floor bed, it is time to brick up the walls of the house to roof height, securing all the door- and window frames in their places in this process. Always place steel and timber window - and door frames on an exact vertical plane, and make sure to provide horizontal support for door frames to prevent them from being bended inwards by the pressure from the surrounding walls. Once again, this is the last opportunity to make minor alterations, but remember, only minor alterations. One can not for instance request a new load bearing wall if a proper foundation has not been provided for it.

Remember, aluminium doors and windows are manufactured and fitted after plastering of the openings, while timber frames can also be installed after plastering. If built in like steel frames, proper care should be taken to prevent the frames from being damaged during the building work.

Before laying the first brick, a damp proof course (DPC) should by provided in the form of a continuous plastic layer the width of the brick wall. DPC is placed under ALL walls to prevent dampness from the earth to rise into the walls.

It is always good building practice to brick up all the walls in the whole building simultaneously. Many builders are guilty of sloppy building practice by bricking up one room at a time, leaving "teeth" in the brick work to tie in the next room's walls.

In areas with a higher rainfall like the Western Cape, it may be advisable to build a cavity wall on all outer walls. In a cavity wall, the two layers of bricks are not built against each other, but a 40mm gap is left between the two layers. These two skins of bricks must however be tied together with evenly spaces wall ties. The gap between the two skins of bricks then prevents dampness from outside to penetrate to the inside of the wall, and also forms an excellent insulator against temperature extremes.

All window frames and openings for wider types of doors like sliding doors must be provided with an reinforced layer over the top of the opening to carry the weight of the wall above the opening. This can be done by either using a pre-fabricated beam called a lintel, or by physically building a lintel using bricks and a kind of wire reinforcement, called brickforce. It is also advisable to build a layer of brickforce into the wall on about every 6th layer of brick work.

All outer (load bearing) walls are built 230 mm wide (2 bricks next to each other), while most non-load bearing (inner) walls are built 115 mm wide. If an inner wall is higher that 3,3 m, it must also be 230 mm wide. Cavity walls are about 280 mm wide.

It is standard building practice to build roof ties into the top 6 layers of the outer walls. Either wire or hoop ties can be used, and the purpose is to tie the roof structure to the walls.

The following deemed-to-satisfy rules should be remembered considering the layout of the different rooms of the house:

No habitable room (excluding a kitchen, scullery and bathroom) shall have an floor area of less then 6 m², with no linear dimension of less than 2 m. The floor to ceiling height of all habitable room shall be not less than 2,4 m over a floor area of 70% of the room. The floor to ceiling height of all other rooms, including kitchen, scullery, bathrooms, passage and foyer shall not be less than 2,1 m.

In order to facilitate natural lighting and ventilation, all habitable room shall have a window opening comprising at least 10% of the floor area of that room, of which at least 50% must be able to open.

It is not necessary to finish off the brickwork of walls that will be plastered, but all un-plastered face brick walls must be grooved out properly between the bricks to have a neat appearance. Face brick walls must be properly washed as soon as possible to remove all dirt and cement stains.

Apart from carrying the roof of the house, the second main purpose of an outer wall is to keep the inside of the house dry! Always use proper hard burnt clay bricks ("clincker" bricks or face bricks) if you don't intend to plaster the outside of the house. If you intend to plaster the outside, the layer of plaster together with the paint layer will keep the water out.

Backfill and water proofing

If the house is built against a slope that has been excavated and backfill is needed on the outside of the house against the wall, such wall must 345 mm (3 bricks) wide. A 0.25 mm thick plastic sheeting should be built vertically into the wall to prevent moist from penetrating into the building. This sheet is built in between the outer and central layer of bricks. Backfilling is done in layers of 150 mm and compacted properly.

The roof

On completion of all the walls, the carpenter can put up the roof structure, comprising either beams for a flat roof, or roof trusses for a pitched roof. Since the roof is an extremely important structural element of the house, it is of cardinal importance that it gets designed by a competent person. Remember, a roof is subjected to its own weight, which can be considerable in the case of a heavy concrete tile roof, and to wind forces, which can be considerable in the case of a lighter sheet metal roof. It is therefore always advisable to have the roof structure properly designed and constructed. These days it is much easier and safer to make use of one of many pre-fabricated roof companies' services. These companies take the exact measurements, conduct a computer-aided design, assemble the trusses in the factory, and erect on site according to specification. This method is required by most local authorities, and also favoured by inhouseplans.com, because an engineering certificate is also issued on completion of the roof structure. Remember to look for participating suppliers in the inhouseplans.com on-line business directory.

The minimum slope of a flat sheet metal roof is 5°, but can go down to 3° if long single span sheeting are used. The minimum slope of a pitched concrete tile roof is 26° without waterproofing, and 17° with an under-tile waterproofing membrane.

During the roof construction, it is the job of the plumber to fit drainage valleys and flashings against walls, chimneys and ventilation pipes going through the roof. Please note that some local authorities require a roof structure inspection, as well as an engineering certificate.

After the roof cover has been completed, the fitting of rain water gutters and down-pipes, as well as fascia boards are optional.

In the case of a flat reinforced concrete roof, it must be designed by a structural engineer. There are various design-and-supply contractors who will also issue an engineer's certificate upon completion. Such a contractor actually needs to be appointed at an early stage, because most local authorities require an engineer's certificate before plan approval. All flat concrete roofs need to be covered with a cement screed, laid with a fall to outlets, as well as a waterproofing membrane. This installation must be done by a specialist who will normally issue a 10 year guarantee. As always, refer to the inhouseplans.com Business Directory for recommended contractors in your area.

The owner-builder should take notice of the fact that on average, once the roof is completed, about 35% of the building costs should be spent.

Plumbing and electrical work

Once the walls have been bricked up, it is time for the plumber to install water pipes and drainage pipes in the walls and floors respectively. The underground waste water drainage pipes should also be installed by now, and inspected by the local authority. This is called the open drainage inspection, and is conducted by the building inspector once the pipes have been installed, but before they are covered with soil. This job must be done by a qualified plumber. The complete water reticulation system is connected to the municipal water connection point on the stand boundary. At this stage the owner will be requested to point out the position of all garden taps. Since it is difficult to change those positions later on, due consideration should be given at this point.

Simultaneously the electrician will install conduiting pipes in the walls and roof structure to accommodate all the electrical cables for the house's electrical system. All electrical wiring start off from a central point, called a distribution box (DB), which again is connected via an underground cable to the municipal electrical connection point on the stand boundary. It is important to choose the position of the main DB carefully. To keep costs down, it must be placed close to the main power connection point, as well as in a practical position and preferably out of sight, like in the garage.

Both the water pipes and electrical conduiting pipes are installed in the walls by chasing grooves into the brick walls and mounting the pipes inside these grooves. Please note that unplastered inner face brick walls require much more ingenuity from the bricklayer, because all pipe work must then be built into the bricks themselves.

Always ensure that the plumber and electrician are qualified and licensed by their regulating authorities. If in doubt, just ask for their documentation.

Plaster work

Once the electrician and plumber have fitted their pipes into the walls, plaster work can commence. This is a specialised trade only to be conducted by an accomplished tradesman. Always take care to use only proper plaster sand.

It should be pointed out here that there are actually three types of sand used in the building trade, varying in their degree of fineness: River sand is the most course, then building sand, while plaster sand is of the finest quality. With the necessary experience, a plastering contractor can achieve various textures in the plasterwork.

Ceilings and Cornice

On completion of the plaster work, the ceiling contractor can move in to fit the ceilings. The ceilings are usually suspended from the roof structure, and be gypsum board, asbestos boards or even timber. The edges of the ceiling are usually rounded off against the walls with some kind of cleat, moulded quarter-round gypsum board, called cornish.

Please note that it will be much easy for the plumber to fit the hot water cylinders (geysers) before the ceilings are installed.

Floor screeds

Once the ceilings have been fitted, the plasterer may move in again to do the finishing layer on the concrete floor slabs, called the screed. The screed is thin layer of sand and cement mix, and is used to make the floor absolutely level. The floor tiles or carpets will be fitted on top of the screed at a later stage.

Finishing trades

At this stage the building site really becomes busy as many different tradesmen hurry around to finish their jobs! The tiler will now be busy fitting wall - and floor tiles where specified, the glazers will be installing window panes, the carpenter will be hanging all the doors and fitting the locks as wells as the curtain rails. Once the house can be closed and locked over night, it is time to install the kitchen and bedroom cupboards and appliances like the stove and oven. The electrician will now complete his job by fitting the wall plugs and light switches, as well as the light fittings, while the plumber will be installing the bathroom fittings, baths, basins, toilets and showers. Various sub-contractors will complete installations like vanity tops, stair- and balcony balustrades, alarm systems, garage doors etc.

After completion, the electrician will issue a certificate of compliance, while the builder and plumber will request a final building and drainage inspection from the local authority. Once again it is important to note that both the electrician and plumber are properly licensed to complete the work. Upon passing a final building and drainage inspection, the local authority will issue an Occupation Certificate. This document is required by law, so never pay your builder his final payment if he can't hand you the Occupation Certificate!

Once all the disciplines have moved out of the house, it is time to install the carpets and skirting boards and get the painter to finish everything off.

Outside work

Before the final inspection, all building rubble must be cleared up and removed. Then landscaping and gardening can commence, including paving where needed, as well as garden and screen walls. Although gardening and paving can commence earlier, care should be taken not to jeopardise the house building work.

General

Refer to the inhouseplans.com specifications and details on the plans for specific finishes. The abovementioned information is a general guideline for a standard house design. Certain designs of the inhouseplans.com houses have very specific detailing.

It always makes good sense to check references of all sub-contractors before appointing them.

It also is reassuring to know whether a sub-contractor is a member of his trade organisation i.e. is the contractor for the aluminium work a member of AAAMSA.

Always refer to the Business Directory for a list of professional bodies.




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