Designing Buildings - User contributions [en]

Helical foundations

2015-04-20T14:44:36Z

Innermedia: Created page with " = Helical Pile Foundations = There are a number of reasons that helical piles are used in both residential and commercial applications. Their history dates back to the early 1..."

= Helical Pile Foundations =

There are a number of reasons that helical piles are used in both residential and commercial applications. Their history dates back to the early 1800's. Alexander Mitchell invented the first helical pile in 1833, a feat that earned him a Telford Medal. It is interesting to note that Mitchell was blind at the time that he invented the helical pile and had only four years of formal education.

== The Physical Attributes of a Helical Pile ==

Helical piles are made of secured steel with low fitted steel plates welded to the base. They resemble household screws used for DIY projects, but on a much larger scale. Tension and compression allow helical piles to stabilise objects in a variety of soil conditions. Machine mounted hydraulic or electrically powered drills are used to install helical piles.

== The Progression of Helical Piling ==

Since their invention, they’ve been used for highway foundations and marine piers. This includes the lighthouse in the Thames Estuary and the 1863 Brighton Pier. Years later, the helical piling technique was utilised for the installation of telecommunication towers. Since the year 2000, it has gradually been adopted as a foundation solution by Network Rail and Highways Agency.

== The Benefits of Installing Helical Piles ==

There are several benefits of using helical piles. They can be installed in confined spaces that are difficult to access. Also, helical piles utilise a low-noise, minimal vibration installation method. This prevents disruption to neighbours and protects the existing landscape from damage. They can be used for repair existing foundations or for building entirely new ones.

The equipment used to install helical piles is often smaller and less expensive than other piling techniques. Furthermore, they can be installed at any time of year and removed as easily and quickly. For example, during the 2012 Olympics, approximately 20,000 seats were installed and uninstalled using helical screw piles. They were then able to be recycled, which would not be possible for concrete foundations.

Helical piles are installed for a variety of new foundations, as well as for a large number of remedial applications such as underpinning or structural slab support.

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=== Related articles on [http://www.designingbuildings.co.uk/wiki/Designing_Buildings_Wiki Designing Buildings Wiki] ===
<ul >
<li>[http://www.designingbuildings.co.uk/wiki/Foundations Foundations].</li>
<li>[http://www.designingbuildings.co.uk/wiki/Geothermal_pile_foundations Geothermal pile foundations].</li>
<li>[http://www.designingbuildings.co.uk/wiki/Pad_foundation Pad foundation].</li>
<li>[http://www.designingbuildings.co.uk/wiki/Pile_foundations Pile foundations].</li>
</ul>
=== External references ===
<ul >
<li>[http://www.fps.org.uk/ The Federation of Piling Specialists].</li>
<li>[http://www.screwfast.com/ Screw Pile Foundations].</li>
</ul>

Loft conversion

2014-07-28T13:29:47Z

Innermedia: Created page with " Loft conversions have been said to increase the value of a home by up to 20%, and can add up to 30% more living space to a house. This valuable area is an excellent development ..."

Loft conversions have been said to increase the value of a home by up to 20%, and can add up to 30% more living space to a house. This valuable area is an excellent development due to the return and the size of the improvement, and can offer a useful alternative to moving house in most instances.

= Types of Loft Conversion =

There are a number of different types of loft conversions. These include Dormer, Velux, Gable End, and Mansard.

== Dormer ==

[http://www.loftworldltd.co.uk/loft-conversions/dormer-loft-conversions/ Dormer loft conversions] are among the most popular because of the additional headspace that they offer. A Dormer is a structure that is attached to the roof to create additional headspace and a window that juts out from the roof, rather than working with the pitch like a [http://www.velux.co.uk/ Velux] window.

== Velux ==

Velux loft conversions take their name from the brand of roof window, and work with the pitch of the roof to simply add skylights rather than making drastic changes to the exterior of the house or the pitch of the roof. These are also popular since they rarely require planning permission and can often be completed in less time than other loft conversion due to the conservative changes to the roof.

== Gable End ==

Gable End loft conversions change the shape of the roof to create upright walls on one or both ends of the building. These offer a lot of additional headroom and usable floorspace compared to Velux and Dormer loft conversions, but take longer to complete and are usually more expensive due to the extensive work required.

== Mansard ==

Mansard loft conversions make the most drastic changes to a house, but add the most space to a loft conversion too. The roof pitch is altered to create a roof that points out at 72 degrees or more, so the roof has 3 walls rather than just 2. Planning permission is often required for this type of loft conversion.

= Building Regulations =

Building regulations approval is required to convert a loft into a liveable space. regulations will ensure that the floor is structurally sound, the roof is stable, the stairs are safely designed, there is reasonable sound insulation, and to ensure that there is safe exit in case of fire.

= Planning Permission for Loft Conversion =

In many instances, loft conversions can be completed as Permitted Developments, which do not require planning permission. However, there are limitations to permitted developments, and if the plans for a loft conversion fall outside of these limitations then planning permission will be required. It may also be necessary if the house is in a conservation area or has already exceeded its allowed Permitted Developments.

Loft Conversions built as permitted developments must:
*Be no larger than 40 cubic meters in a terraced house, or 50 cubic meters in a detached or semi-detached house
*Not extend beyond the existing plane of the roof
*Be build in materials that are similar in appearance to the existing house
*Not have any verandas, balconies, or raised platforms
*Be set as far back as reasonably practicable
*Not overhand the outer face of the wall of the original house

= Further Reading =

[http://www.planningportal.gov.uk/permission/commonprojects/loftconversion/ Planning Portal]

[http://www.loftworldltd.co.uk/ Types of Loft Conversion]

[http://www.fdean.gov.uk/media/Assets/Planning-BC/documents/approved%20documents/DOMESTIC_LOFT_CONVERSION_GUIDANCE_EDITION_4.pdf Building Control Guidance for Loft Conversions]

Tree hazard survey

2014-07-22T13:24:32Z

Innermedia: Created page with " Landowners have an obligation to ensure that hazardous trees are properly managed using pro-active systems - this is a legal requirement as poorly managed trees can harm people ..."

Landowners have an obligation to ensure that hazardous trees are properly managed using pro-active systems - this is a legal requirement as poorly managed trees can harm people and cause considerable property damage.

= Laws Concerning Tree Management =

A number of UK laws require landowners to routinely inspect and manage the trees on their property. These laws include:
*[http://www.legislation.gov.uk/ukpga/1974/37/section/2 Health & Safety at Work Act 1974 s 2 & 3]
*[http://www.legislation.gov.uk/ukpga/Eliz2/5-6/31/contents Occupier's Liability Act 1957]
*[http://www.legislation.gov.uk/ukpga/1984/3/contents Occupier's Liability Act 1984]
*[http://www.legislation.gov.uk/uksi/1999/3242/contents/made Management of Health and Safety at Work Regulations 1999]
*Donoghue v. Stevenson 1932 (which established legal precedent)
*Noble v. Harrison 1926
*[http://www.flac.uk.com/wp-content/uploads/2009/12/Chapman-v-Barking-and-Dagenham-London-Borough-Council-1997.pdf Chapman v. Barking & Dagenham London Borough Council 1997]
*Poll v. Bartholomew 2006

As part of the obligations outlined in this series of laws, landowners must identify areas of trees by risk zone (high, medium, low) and actively manage trees within those zones. Records should be kept to prove the management is taking place.

= Tree Hazard Surveys as Part of Active Management =

Surveys help to classify risk and produce tree surgery specifications, as well as compiling reports as proof of management and log dates for future inspections.

Tree Hazard Surveys typically include:
*Preparing a tree safety policy
*Implementing tree management systems
*Completing internal decay tests on hazardous trees
*Assessing tree dimensions and crown spread
*Noting tree age class, physiological condition, and life expectancy
*Assessing tree condition and landscape value
*Recommending tree works
*Creating priorities and timescales for work
*Estimating costs for future work

== Instruments for Completing a Survey ==

As surveys require in-depth knowledge of arboriculture and tree lifecycles, as well as health and safety requirements, most of the requirements for tree surveys are met by the knowledge and understanding of the surveyor.

However, assessments such as internal decay detection include some equipment such as digital microprobes and picus sonic tomographs to assess how the tree's structure is affected.

= Further Reading =

[http://www.forestry.gov.uk/PDF/fcpg13.pdf/$FILE/fcpg13.pdf Forestry Commission Hazards from Trees Guide]

[http://www.ground-control.co.uk/tree-hazard-survey/ Breakdown of a Tree Hazard Survey]

[http://www.hse.gov.uk/foi/internalops/sims/ag_food/010705.htm HSE Management of Risk from Trees and Branches]

Pile foundations

2014-07-21T10:52:54Z

Innermedia:

Foundations provide support for structures, transferring their load to layers of soil or rock that have sufficient bearing capacity and suitable settlement characteristics. There are a very wide range of foundation types suitable for different applications, depending on considerations such as:
*The nature of the load requiring support.
*Ground conditions.
*The presence of water.
*Accessibility.
*Sensitivity to noise and vibration.
*Proximity to other structures.
*Project timeframes.

Very broadly, foundations can be categorised as shallow foundations or deep foundations. Shallow foundations are typically used where the loads imposed by a structure are low relative to the bearing capacity of the surface soils. Deep foundations are necessary where the bearing capacity of the surface soils is insufficient to support loads imposed and so they are transferred to deeper layers with higher bearing capacity.

Pile foundations are deep foundations. They are formed by long, slender, columnar elements typically made from steel or reinforced concrete and sometimes timber. A foundation is described as piled when its depth is more than three times its breadth (Atkinson, 2007).

Pile foundations are principally used to transfer the loads from a superstructure, through weak, compressible strata or water onto stronger, more compact, less compressible and stiffer soil or rock at depth, increasing the effective size of a foundation and resisting horizontal loads (Tomlinson & Woodward, 2008). They are used for large structures, and in situations where the soil under is not suitable to prevent excessive settlement.

Generally piles are classified as; end-bearing piles (where most of the friction is developed at the toe of the pile, bearing on a hard layer) or friction piles (where most of the pile-bearing capacity is developed by shear stresses along the sides of the pile, suitable when harder layers are too deep). Most piles use some end-bearing and some friction, in order to resist the action of loads.<br/>

Piles are most commonly driven piles, prefabricated off site and then driven into the ground, or bored piles that are poured in situ. If the boring and pouring takes place simultaneously, the piles are called continuous fight augured (CFA) piles.

The choice of pile depends on the location and type of structure, the ground conditions, durability of the materials and cost. Driven piles are useful in offshore applications, are stable in soft squeezing soils and can densify loose soil. However, bored piles are more popular in urban areas as there is minimal vibration, they can be used where headroom is limited, there is no risk of heave and it is easy to vary their length (O’Sullivan, 2010).

Mini piles (or micro piles) are used where access is restricted, for example underpinning structures affected by settlement. They can be driven or [http://www.designingbuildings.co.uk/wiki/Screw_pile_foundations screw piles]

Pile walls can be used to create permanent or temporary retaining walls. They are formed by placing piles directly adjacent to one another. These can be; closely-spaced contiguous pile walls, or interlocking secant walls, which depending on the composition of the secondary intermediate piles can be hard/soft, hard/firm or hard/hard secant walls.

Geothermal piles combine pile foundations with closed-loop ground source heat pump systems. They provide support to a structure, as well as acting as a heat source and a heat sink. In effect, the thermal mass of the ground enables the building to store unwanted heat from cooling systems and allows heat pumps to warm the building in winter (Boennec, 2008). Generally, ground source heat pumps extract heat from the ground by way of underground pipes which are laid either horizontally or vertically in the ground (Boennec, 2008). In geothermal piles, the pipe loops are laid vertically, within the piles themselves. See Geothermal pile foundations for more information.

= Find out more =

=== Related articles on Designing Buildings Wiki ===
*Foundations.<br/>
*Geothermal pile foundations.
*Temporary works.

=== External references ===
*[http://www.fps.org.uk/ The Federation of Piling Specialists].

[[Category:Construction_techniques]]
[[Category:Products_/_components]]

Screw pile foundations

2014-07-21T10:52:18Z

Innermedia: Created page with " Screw pile foundations are a type of [http://www.designingbuildings.co.uk/wiki/Pile_foundations pile foundation,] with a helix near the pile toe so that the piles can be screwed..."

Screw pile foundations are a type of [http://www.designingbuildings.co.uk/wiki/Pile_foundations pile foundation,] with a helix near the pile toe so that the piles can be screwed into the ground - the process and concept is similar to screwing into wood.

A screw pile may have more than one helix (also called a screw), depending on the usage and the ground conditions.

== Screw Pile Foundation Installation ==

Installing screw pile foundations takes considerably less time, machinery, and cost than installing a standard concrete foundation. Depending on the size of the piles, any size plan can be used for the installation including hand-held machines. In many instances, only one machine is required for a steel, screw pile foundation installation. Screwed piling is installed with a hydraulic torque drive.

== Screw Pile Usage ==

Screw pile foundations are the preferred choice for a number of industries. While they were originally developed for the nautical industry, they are now used by rail, road, telecommunications, and civil engineering. Screw piles can bear large tensile and compression loads, so they are often used for masts, signs, and retaining structures.

== Screw Pile Benefits ==

In addition to the strength of the foundations, they offer some unique benefits which have increased their usage in recent years. These include:
*Ease of installation (using fewer machines and taking less time)
*Faster installation
*Lower carbon footprint
*No need to remove soil from the site
*Ability to install in close proximity to existing structures
*Ease of removal when no longer needed

= Find out more =

=== Related articles on Designing Buildings Wiki ===
<ul >
<li>[http://www.designingbuildings.co.uk/wiki/Foundations Foundations.]</li>
<li>[http://www.designingbuildings.co.uk/wiki/Pile_foundations Pile foundations].</li>
</ul>
=== External references ===
<ul >
<li>[http://www.fps.org.uk/ The Federation of Piling Specialists].</li>
<li>[http://www.screwfast.com/ Screw Pile Foundations].</li>
</ul>