Glazing

Introduction

The use of glass in the building industry has increased greatly over the last few decades. The versatility of flat glass - the genetic term used to describe unbowed glass used in the glazing of windows and doors -has enabled it to be used in many ways, which ultimately enhance the quality of life. Glass has been adapted to reduce both heat loss and noise with double and triple glazed units. Laminated and toughened glass offers greater safety than ordinal), sheet and float glass; laminated glass gives the added advantage of increased security protection. Wired glass prevents the spread of flames, while solar control glasses (specially coated and tinted) help reduce the effects of radiant heat from the sun. Patterned and obscured glass afford a greater degree of privacy together with a decorative quality. 

There are also numerous materials for the fixing of glass to frames, from traditional linseed oil and whiting putty, timber beads screwed or nailed to frames, to modem sealants, non-setting compounds, mastic tapes and so on. We shall, however, be concentrating on the basic methods by which glazing is fixed to frames. 

Estimating for glazing 

In order to estimate the costs of a particular item of work accurately, it is necessary to have details of the following: 

Linings, Partitions and Surface Finishes

Plasterboard

Plasterboard is available in various types for different uses, and in various widths, lengths and thicknesses. The main manufacturer of plasterboard in Britain is British Gypsum Limited. Therefore that company's products are described, as they are those most likely to be encountered on a day-to-day basis. 

Gyproc wallboard and plank Gyproc wallboard is a dry lining plasterboard consisting of an aerated gypsum core encased in a durable paper liner, suitable for application to internal surfaces. The boards have one face of an ivory coloured finish for use where decoration will be applied direct, that is where joints are filled and taped, and the other face of a grey, finish which can be coated with plaster. 

There are three types of edge profile for differing joint requirements: 

Low cost soil cement mortar block work & brick work

You can read our full article about normal brick work and block work below link

How to make a Post tension slab / PT Slab

This videos about PT Slab / Post Tension Slab

Plumbing installations

Introduction

This chapter covers standard plumbing installations. Mechanical heating/cooling/refrigeration systems, and ventilation and air conditioning systems, are more specialized forms of mechanical engineering and are generally carried out by specially trained tradesmen. Examples for these systems will not be given. However, the principles of the plumbing examples can be applied to these other systems, bearing in mind the differences in wage costs and the need for specialized tools and plant, especially for handling bulky or heavy items. 

The SMM7 sections are: rainwater pipework/gutters; foul water drainage above ground; pipelines; pipeline ancillaries; and sanitary appliances/equipment. 

All-in rates for pipe

Pipe is available in a bewildering variety of materials and types. For the plumber, plastics, metal and composition materials are the most common. In these materials, pipes are manufactured to carry hot and cold water; other liquids, including those that are corrosive, flammable, toxic, etc.; gases; foul water, rain water and waste water; and so on. Such pipes share certain features which make it possible to treat them as a single class for measurement, and also allow us to generalize in the explanation of how to determine all-in rates. 

Pipe is supplied in lengths or coils, rigid or brittle materials being in lengths and flexible materials being in coils. The most common length is 6 m. However, some pipe is supplied in shorter or longer lengths, especially where the joint is formed as part of the pipe, as in PVC or cast iron soil pipe with spigot and socket joints. Cast iron pipe and gutters are still supplied in imperial lengths of 6 feet. Variety of lengths for pipe with integral sockets (say 1, 2, 3 and 4 m) reduces waste, because every cut produces a length with a joint and another length without a joint! 

Coils of 25, 50, 100 or 150 m are common, but some pipe is supplied in 30 m or even 60 m coils. The coil length is dictated as much by what the plumber wants to keep in stock as by old traditional manufacturing processes. For example, it might not have been possible to extrude more than 30 m of a particular pipe in one operation, and therefore it became standard practice to supply in coils of that length. The pipe must inevitably be cut to length. The shorter are the cut lengths, the greater is the labour, the fewer are the joints in the running length and, depending on the rigidity of the pipe and the appliances served, the fewer are the fastenings to hold the pipe in place. 

Pipe material varies in its bending ability as follows: 

• Bends can be easily made, e.g. in polyethylene and polybutylene water pipe (although of large radius)
• Bends can be made with apparatus, e.g. in half hard copper pipe (BS 2871 Table X) for hot and cold water supply, using springs or a light bending machine 
• Bends cannot be made and elbows or bent couplings have to be used, e.g. in cast iron pipe, uPVC soil pipe or hard thin wall copper pipe (BS 2871 Table Z). 

The material is always fully specified so that identification is positive. 

There is generally a standard method of fixing the pipe in position. Non-standard fixings must be fully specified in the bill item or preamble. The background to which the pipe is fixed is also given. Backgrounds are tabulated in the general rules to SMM7, 8.3(a) to (e). 

Structural Steelwork and metalwork

Introduction 
Structural steelworks and metalwork are specialist elements of the building and as such are normally the subject of a subcontract. It would be extremely rare for the contractor's estimator to be involved in pricing other than, for example, an isolated steel section to be used as a lintel, or the fixing in position of a fabricated metal window or metal balustrade.
SMM7 takes account of the specialist nature of these elements of construction in its requirements for dimensioned drawings from which the specialist can measure the work involved. The relevant SMM7 sections are as follows:

GIO Structural steel framing
G12 Isolated structural metal members
L11 Metal windows/roof-lights/screens/louvres
L21 Metal doors/shutters/hatches
L31 Metal stairs/walkways/balustrades

This chapter deals with a selection of these elements.

Isolated structural metal members (G12) 
Isolated structural metal members are the most common example of steelwork fixed in position by the contractor's own operatives. Proprietary steel lintels over window and door openings will be fixed in position by bricklayers in the course of their work. Other heavier sections may require craneage.

Metal windows/rooflights/screens/louvres (L11) 

Metal windows are supplied to site complete and ready for fixing to a timber subframe. Aluminium windows are supplied fully finished and often pre-glazed. Example 13.3 assumes that a timber subframe is already in position and has been priced under the timber item L10. 

Aluminium windows are delivered to site with tape protecting the finish and with labelling on the glass. The labelling is to inform operatives that the windows are glazed, and helps to prevent, for example, scaffolding tubes being passed through the glazed window. 

Pre-glazed units will require careful handling, storing and placing in position, which is reflected in the rate. 

Woodwork Joinery - Second Fixings and Finishings

Introduction 

This part of the estimating for woodwork in modern practice is now very much more concerned with the fixing of pre-finished units. The idea of these units is not new. However, the rapid development of new materials and technologies, together with economic pressures on the building industry, have accelerated the demand for and use of pre-finished units. The joiner today is no less skillful than his predecessor, but has new skills and techniques which have boosted his output. 

Floors and decks are still boarded with softwood and hardwood strip. However, there are sheet materials now available which one can almost consider to be pre-finished units laid over joists. Indeed, some of these sheet materials have peelable coverings to facilitate leaving a clean floor or deck after the works have been completed. 

Doors can now be obtained not just pre-finished but complete in their frames, with architraves fixed one side and loose the other. The frame is placed into the opening in the wall or partition and fastened with frame anchors or screws. The protective polythene wrapper is peeled off, and the door is there complete with all its ironmongery! 

Similarly, windows are coming on site already glazed and with all ironmongery factory fitted. They are fixed into openings in walls with framing anchors or brackets and the protective wrapping is removed. The window is then fully functional during building, keeping the weather out and letting light in. Even window boards and bed moulds are part of the kit to be added after fixing the window into position. 

The multitude of fasteners available has already been discussed in the previous chapter, as have the various difficulties encountered in working with softwoods and hardwoods. 

Before going on to some examples of rates, the reader should remember that we have been working with a squad of 1 labourer and 5 craftsmen costing £9.30 per craftsman how. This hourly rate will continue to be used in this chapter.