- May 5, 2020
Quantity Surveying 12
AHouse Construction Report
AHouse Construction Report
Task One: Site Investigation and Groundwork 3
Task Two: Foundations 6
Task Three: The External Walls 11
Task Four: Floors 19
Task Five: The Roofs 21
Reference List 23
Itis important that proper procedures be followed when constructingstructures such buildings. The construction procedures are whollydependent on the geological properties of the site where thestructure is to be constructed. Also, thorough site investigationshould be carried out to avoid any failures in the future. Subject toresearch, site investigation is the procedure through whichgeotechnical, geological, and other important ground condition data,which may influence the execution of a construction are studied. Thisreport aims to explore the various steps of a building construction,from the foundation level to roofing.
TaskOne: Site Investigation and GroundworkSignificanceof Site Investigation in Choosing Foundation Type
Siteinvestigation is a procedure by which geotechnical, geological, andother important ground data, which may influence the construction ofa building are gathered and taken to the lab for a scientific study.Through the data gathered, the durability and the general safety ofthe occupants of the proposed building can be evaluated. Soil androcks have varied characteristics that may either affirm or nullify aproposed design of a building (An & Di 2016. Therefore, thechoice to construct a building build on a given site is usuallypremised on its entire appropriateness from the perspectives ofengineering.
Someof the site data that are needed include rock formation and theirgeological structure, soil profile, bearing capacity, shear strength,and plasticity index. These data are very significant in anyconstruction of heavy structures from low-rise buildings toskyscrapers and water structures, such as weirs and dams. Theinformation regarding the aforementioned parameters is essential inselecting the foundation type for any particular structure. It isbecause the bearing capacity of a soil varies from one type of a soilto the. Since the discovery of soil engineering, the black cottonsoil have been known to have low bearing capacity than sand. Thisposes a serious danger to foundation and ground floor slabs becauseof swellings that result from ground pressure uplift (Dematteis &Soldo 2015). Consequently, having information regarding the type ofsoil found on a particular site will inform the type of foundation tobe chosen, such as raft foundation. On the other hand, pad foundationfooting is mostly applicable for sand soils due to low differentialsettlement.
Figure1. Uplift Pressure in Clay Soils (An & Di 2016).
Excavationand Plant Safety
Excavationsmust follow the set safety procedures, especially, if on cohesivesoils and in frail rock. This is because such soils can only standunsupported for periods running from 30 seconds to 30 days (An &Di 2016). In any case, care should be taken since it is difficult topredict the exact time the sides will be will collapse. It isexpected that both sides of the excavated area be supportedfirmly.Support is expected to forestall collapse and to guarantee thesafety of the building occupants and the neighbors. After thesupports have been erected on both sides of the excavated area, thezone of influence needs to be estimated as shown in Fig. 2 below(Kelly, Graham, & Male 2014). The mechanical plants such asvehicles, excavators, or some other overwhelming loads ought not tobe situated in the `zone of influence` of excavation. The groundsupport that is recommended and introduced should be placed by askilled personnel, such as a geotechnical specialist, to prevent thedynamic forces that may cause the side-walls of an excavated area tocollapse.
Thedetermination of the zone of influence will rely upon the groundconditions. It is the zone in which there may be an influence on theexcavation, including conceivable ground collapse. Any material willadd a load to the region where it is put. Therefore, is critical thatmaterials are not put or stacked close to the edge of any excavatedareas. Moreover, to lessen the danger of ground collapse, excavatedor free material ought to be put away from the excavation. Theexcavated material ought to be set outside the determined zone ofinfluence. On the other hand, a ground support ought to be plannedand introduced to convey the extra loads, including any ground waterpressures and saturated soil materials.
Figure2 Ground Support and Zone of Influence (Riley& Cotgrave 2008).
Figure3. Strip Foundation (Riley& Cotgrave 2008).
Ithas been observed that the strip or fill foundation, as shown above,is favorable in sites with expansive soils such as clay. The mainreason for such observation is based on the fact that there islimited if no distress to the ground floor slabs due to the presenceof suspended rafts (Ngan-Gillard al. 2010). Also, the disturbancescaused by differential settlement of clay soil are very minimal,thusleading to durability and safety of structures(Kelly,Graham, & Male 2014).
Siteinvestigations must be carried out to uncover the likely soilconditions of the proposed site after which, a stepwise methodologyis employed to execute various structural elements.
Thefollowing procedure should be followed in this case:
Treesand hedges in site location should be cleared to create room forexcavation and consequently, construction of various structuralelements.
Trenchfill foundations in expansive clay soils have a wider zone ofinfluence. As such, there is a need for heave precautions.Compressible soil materials ought to accurately put in place tocontain the swelling clay soils in the excavated area.
The foundation`s sides must be as vertical as possible and should never be battered at any point.
The ground floors where the clay soil settlement is expected should be suspended with a ventilation void space under it. This will eliminate any heave circumstances that may ensue due uplift pressures.
Duringsetting, the sides of the excavated trench should be kept verticalwhile the floor is leveled. The following should be taken intoaccount:
Ensure that the design thicknesses of diver leaves and the recommended exaction dept as per the engineering drawings.
The substructure must be built halfway on the excavated trench foundation.
Ensure that the diagonals and structural estimation are precise.
Excavationand Blinding Layer
The cavity wall to be central on blinding layer.
Minimum strength and thickness of blinding layer should be 15kN/m2 and 100mm respectively.
Foundation trenches must be widened at the pier locations to ensure the recommended projection dimension.
Foundation width should not be less than that recommended in the Building Regulations manual.
Unless structurally specified, where concrete is to be cast directly into the earth, the reinforcement to be used must have not less than 70mm nominal cover.
The trench bottom must be horizontal as possible.
Waterand Debris in Trenches
Any debris and water present in the foundation trenches must be removed before concrete casting is commenced.
ConstructionJoint and Reinforcement
Thesteel reinforcement bars for the foundation strip should be as perthe design specified sizes.
If plastic shuttering is to be used for the ground beams, all care ought to be taken so that shuttering or the earth backfill material supports formwork properly before concrete is cast.
The formwork must be straight for the correct depth of cover to the steel reinforcement bars to be achieved.
Unnecessary concrete joints should be avoided as much as possible
Steel or corrugated formwork or even clean and smooth timber boarding should be used.
The trench foundation dimensions must be able to accommodate the cavity walls as centrally as possible.
The concrete blinding layer for the foundation must be leveled.
The diagonals must correspond to the design specifications before erecting the substructure cavity walls.
Masonry cavity walls should be set out to achieve the recommended cavity widths.
Brickwork must be set to the edges of the trench foundation or corbelled to ensure that there are no rectify cavity widths.
GroundBearing Floor Construction
Topsoil and any organic matter must be scrapped off and removed and the underlying layer leveled.
Ground floor slabs to should constructed as specified and the fill earth material must be compacted in several layers not exceeding 225mm with no pieces that go through a 75mm ring diameter.
In cases where the depth totals of earth fill material under the ground floor slab is more than 600mm, a suspended raft foundation floor construction to be provided.
Fill material used must be free from any harmful and toxic substances.
Fill material should be prepared as certified by a recognized competent laboratory procedure regarding their engineering fitness for purpose. They must also be chemically checked and analyzed before use.
ExternalWalls Damp Proof Membrane
Check that the hardcore infill is compacted to the recommended degree and covered with blinding made of sand to ensure that even support is provided for the DPM (insulation).
DPM membranes must not be less than 1200 gauge. The thickness can be increased and should be a Radon or any other gas barrier is to be required. Additional provisions for the laps or service pipe insertions also apply.
DPM sheets should be overlapped by not less than 150 mm.
In cases that DPM is sited underneath the concrete floor slab, it must also be underneath any insulation material level, especially, when that insulation material is less resistant to ground impurities.
The DPM to be turned up at floor slab edge and lapped below the DPC for the complete thickness of the interior leaf to make a continuous barrier.
TaskThree: The External Walls
Figure4. Material Member Specifications (Dematteis & Soldo 2015).
Conventionalmasonry walls must be constructed with an interior and exteriorleaves while a cavity is provided separating the two. It must beconstructed as per the following guidelines:
The cavity must have not less than 50mm width
It must be kept free of mortar snots so that it is never bridged
The exterior and interior leaves must be tied appropriately as per the design specifications.
The cavity may be completely or partially insulated, depending on wind and rain exposures. For incomplete fill insulation, not less than 50mm of the cavity must always be provided.
Thecavity wall section is as shown below.
Figure 5. Cavity wall section (Emmitt& Gorse 2006).
Wallties must meet the following conditions:
They must be as specified in BS EN 845-1.
They must be suitable for the recommended width of cavity and be not less than 50mm leaf bearing
They must be laid to a minor fall towards the external leaf and to have the capability to bind insulation against the inner leaf for incomplete fill scenarios.
Lateralrestraint strapsmustbe provided where necessary and must be as per the designspecifications.
Brickand block suitability
Facing masonry bricks must be durable especially regarding frost and moisture resistance.
All external masonry block work must be rendered or to be finished with a durable cladding.
Masonry blocks always vary in color. The color chosen must be as per the client needs.
Mortar category over DPC course must be by design manual to ensure adequate durability, workability, and strength.
Batching and mixing machines and equipment must be kept clean to avoid contaminations.
The mortar should be mixed by the mixing machine or the already mixed ones to be used.
Mortar must be carefully and constantly proportioned, and then methodically mixed using an automatic mixer, except for very miniature quantities.
Thisshould be carried out by a licensed quantity surveyor.
Thefoundation dimensions should be fully considered and thoroughlychecked (Dematteis & Soldo 2015).
Formworkor Plastic Shuttering
TheFormwork or plastic shuttering should be carried out as outlined inthe specification books. The figure below gives more details aboutthe specifications.
Figure6. Formworkor Plastic Shuttering (Emmitt& Gorse 2006).
Settingout of the walls
Thetrench foundations must be of the correct width to accommodate thecavity walls centrally.
Figure7. Wall setting (Panda et al. 2014).
Drainageand Service Entries
Thedraining pipes passing through the external walls must be secludedthrough lintels and or ‘rocker pipes’.
Figure8. Drainage and Service Entries (Emmitt& Gorse 2006).
TheDPC membranes should be provided as shown below in the figure below.
Figure9. Damp Proof Membranes (Kelly,Graham, & Male 2014).
HorizontalDamp Proof Courses
Wherea DCP membrane is to be sited over the floor construction but put inplace laid before the superstructure is fully completed, it isrecommended to install a 450 mm wide of DPC, which must be lappedonto the interior leaf before cavity wall (Panda et al. 2014).
Figure10. Horizontal Damp Proof Courses (Kelly, Graham, & Male 2014)
Windows& External Door Frames
Windows& External Door Framesmustbe carried as per the design specifications.
Figure11. Windows & External Door Frames (Kelly, Graham, & Male2014).
Roof& Guttering must be constructed as per the design specifications
Figure12. Roof and guttering (Kelly, Graham, & Male 2014).
Figure13. Floor (Kelly, Graham, & Male 2014)
There should be no less than 50 mm void space between the ground floor beams and fill earth material.
The beams should be placed onto a DPC membrane at the bearings.
The beams should be suspended by brick piers of not less than 200 mm by 200 mm cross section surface.
It should be ensured that the cavity material fill is not less than 225 mm below the lowest level of the DPC.
The ventilation voids at the two opposite cavity walls must be provided to the ground floor one with a required provision of not less than 1500 mm2 /m run.
A DPC should be provided above the finished ground floor slab just under the party wall.
SafeConstruction method for the Upper Floor
Figure14. Upper floor. (Panda et al. 2014).
Engineeringevaluation and detailed design
Allthe timber frames should be designed within the specified parametersof BS 5268 or Eurocode 5 (BS EN 1995-1).
Itis significant that the slab is put up within the tolerancesspecified for the timber frame since the cavity wall panels areplaced on sole metal plates, which rest on the slab.
Thescaffolding is necessary to ensure the safety of the occupant. Allthe scaffolding smust meet the recommended threshold.
Theteam charged with site erection must be completely trained andbriefed properly to ensure that the floor joists and timber frame areconstructed in a safe manner and accordance with the designrequirements/
TaskFive: The Roofs
Figure15. The roofs (Panda et al. 2014).
MaterialSpecifications for Warm Deck Flat Roof
The finished roof should have a slope of not less than 1 in 80.
Theroof should be drained in one edge or two edges.
­The traditional gutters are enhanced than interior outlets. ­
The waterproofing should extend up adjacent to the cavity walls of not less than 150 mm (6 in) in all situations from the roof surface.
The top most edge of the waterproofing material should be protected by a nominal cover flashing.
The insulation must be as per the Part L of the Building Regulations.
The bitumen membranes should be covered from the sun as per the surface protection manual.
All the roof materials such as insulation and membrane sections must be constructed to guard against wind forces.
Themain aim of this report was to explore the various stages of buildingconstruction from the foundation level to the roofing. The variousstructural elements such as beams walls, floor joist, and trusseshave been evaluated by considering safe and economic constructionmethods, as well as material specifications. Specifically, the reporthas focused on the soil type and ground conditions. After reviewingthe various aspects of a building construction, it can be concludedthat safety is paramount. Therefore, it should be a majorconsideration in all the stages of building construction, from siteinvestigation to the finishing operations.
An,Z, & Di, Q (2016). `Investigation of geological structures with aview to HLRW disposal, as revealed through 3D inversion ofaeromagnetic and gravity data and the results of CSAMTexploration`, Journalof Applied Geophysics,Science, pp 245-251.
Dematteis,A, & Soldo, L (2015). The geological and geotechnical designmodel in tunnel design: estimation of its reliability through theR-Index`, Georisk:Assessment & Management of Risk for Engineered Systems &Geohazards,9, 4, p. 250-298.
Emmitt,S. & Gorse, C. (2006) `Barry`s Introduction to the Constructionof Buildings` 1st Edition Blackwell 1405110554
Kelly,J, Graham, D, & Male, S (2014). ValueManagement of Construction Projects,Chichester, West Sussex, United Kingdom: Wiley-Blackwell, DiscoveryeBooks,
Panda,M, Mohanty S, Pingua, B, & Mishra A. (2014). `Engineeringgeological and geotechnical investigations along the head racetunnel in Teesta Stage-III hydroelectric project, India`, EngineeringGeology,181, pp. 297-308.
Riley,M. & Cotgrave, A. (2008) `Construction Technology 1: HouseConstruction` 2nd Edition