Internal Walls PDF

Internal Walls Module Leader: Graham Terry Building Technology Internal Division of Space Learning Outcomes At the end of this session you should be able to: Definition Early partition system Modern load bearing partitions Modern non-load bearing partitions Dry linin...

Internal Walls Module Leader: Graham Terry Building Technology Internal Division of Space Learning Outcomes At the end of this session you should be able to: Definition Early partition system Modern load bearing partitions Modern non-load bearing partitions Dry lining Building Regulations.  A partition is an internal wall and its primary function is to divide the space within a building into rooms It may be load bearing or non-load bearing Partitions The partition should provide: Strength and stability Sound insulation Fire resistance Early partition system A typical half brick wall is shown Load bearing partitions of this type needed their own foundation to distribute the load Non-load bearing partitions would probably sit on either the raised timber floor or concrete slab. Lath & Plaster https://www.designingbuildings.co.uk/w/images/5/5 2/xLath_and_plaster.jpg.pagespeed.ic.fI1fq9VTq3.jpg https://2.bp.blogspot.com/- JPe3nA0pZ4I/VMMmd4jONeI/AAAAAAAACpE/YDy_Z- YNz4A/s1600/lath%2Band%2Bplaster.jpg Load Bearing Walls Modern load bearing partitions Load bearing partitions are usually built from blocks 100 mm wide Dense concrete blocks offer the best sound insulation and lightweight blocks the best thermal insulation Blocks will require a foundation or thickening of the slab depending upon the loads taken Block partitions should be adequately tied to the structure or load bearing walls to provide lateral stability and continuity as a sound barrier. Modern non-load bearing partitions Blockwork Thinner blocks can be used which are 50 or 75 mm wide Must be tied to the external walls to provide stability.  Drylining to masonry- ‘sticking’ Walls may be drylined with plasterboard or plasterboard laminates, fixed with adhesive dots or nailed or screwed to continuous wooden battens or metal studs may also be used. 12.5 or 15 mm standard boards may be used, but not 9.5 mm boards on external walls. The sequence is as follows. Measuring up, including identification of high spots and out-of-squareness and verticality of walls Marking out, allowing 15 mm clearance at heads of boards, making sure the correct side of the board is identified Cutting to fit Fixing – either screwed or stuck Boards are lifted to provide a close fit with the ceiling. Thermal laminate boards may not be suitable for fixings for radiators and cupboards unless the fixing device goes into the structural wall. Problems have been recorded with external walls drylined with plasterboard, where the expected thermal insulation has not been achieved. This is almost certainly due to the practice of not providing continuous seals of the air space behind the plasterboard, particularly at head and foot and around window openings  Dot & Dab Fist-sized blobs of plasterboard adhesive are trowelled onto the blockwork. Solid adhesive along the bottom for skirting fixing. Solid adhesive in corners. Board is pressed against the adhesive and wedged up to the ceiling with packers. Board is levelled with a straight edge. Dries within 1hr. Specialist boards at reveals  Channels An alternative to dot and dab: Metal channel is embedded into plasterboard adhesive and leveled vertically and horizontally. Plasterboard is screwed to channels when adhesive is set.  Jointing and finishing Screw holes and joints are filled with filler. Scrim is laid in the joint filler. More filler is added over the top. Once dry the filler is sanded and ready for direct decoration. Quick, cheap, less mess than traditional plastering. Less skill required. Less water is added to the building. Jointing & Finishing  Skim coat plastering Requires scarce specialist skills. 2–5 mm of plaster applied in two coats. Thin coat angle and mesh beads required for corners. Messy wet trade introduces water into the building and requires drying time. Excellent surface finishes are obtainable. For durability: Thistle Hardwall and Durafinish 60% more hardwearing than standard plaster Increased resistance to accidental damage Can be used on plasterboard or undercoat plasters, or for replastering and repair work on previously finished walls Ideal for high-traffic areas including corridors, stairwells and canteens in healthcare, leisure, social housing, education or office buildings Modern non-load bearing partitions (cont.) Timber stud partitions Easy to construct, lightweight, adaptable and can be clad and infilled with various materials to give different finishes and properties A modern stud partition consists of a framework of timber covered with plasterboard both sides Thicker the plasterboard the better the sound insulation and fire protection Timber non-load bearing partitions consist of 75 x 50 mm studs Stud spacing is governed by the size and spanning ability of the facing or cladding material. Modern load bearing partitions (cont.) In new two storey housing they are only likely to be found on the ground floor where their function is to support the 1st floor joists and, of course, divide space In some case, e.g. timber frame housing, they may also have to help stiffen the structure. Timber partitions Studwork formed from 100 x 50 softwood timber. Fixed with long steel nails. Studs are spaced at 400/600 centres. Sole plate forms basis of wall- nailed to floor structure. Head plate forms the top- nailed to ceiling soffit. Studs are skew nailed into sole and head plates. Noggins at sole and head plate, and at half height provide stiffening. Quick, cheap, simple to construct and remove. Timber stud partitions  Proprietary systems These are manufactured by British Gypsum Solid wall– non-load bearing Panel wall – non-load bearing Metal partitions – load bearing All are quick to erect and are self finished for direct painting.  Metal track systems Steel channel forms partitions instead of timber. Sole plate sets out the wall. Length can be cut with chop saw or snips. Studs slot into rails and secured with self-tapping screws. Holes pressed into studs for cables and pipes. Metal track Metal ceiling systems Metal ceiling systems meet the performance requirements of many different types of building and locations within the building. Strength, fire, thermal, sound and vapour permeability can all be adjusted. Ceiling systems combine speed of installation with ease of levelling and alignment. Solid wall Consists of 3 - 4 layers of plasterboard with 38 x 25 mm timber battens which are fixed to the walls, ceiling and floor An outer layer of plasterboard is nailed to the frame and the plasterboard for the middle layer is then cut to fit between the floor and ceiling battens. This is attached using a bonding compound to the outer plasterboard. The final layer of plasterboard is bonded to the middle layer and nailed to the frame. Panel wall Formally called a paramount partition Two layers of wallboard bonded to a cellular core of stiff cardboard. The 50 mm thick partition is quick to erect and shrinkage of material is kept to a minimum Timber battens are used at floor, external wall and ceiling to secure the partitions. Metal framing A frame of galvanised mild steel studs and noggins are used with a Gypwall board screwed to both sides of the frame. Dry lining This involves covering the internal surface of the wall or partition with plasterboard, insulating fibre board, hardboard, timber boards or plywood.  Sound insulation improvements The intensity of unwanted sound that increases vibration of a separating wall or floor can be reduced to some extent by attaching a lining to the existing structure. Plasterboard or other dense material is suitable but this will have only a limited effect as the lining will also vibrate and radiate sound. The most effective solution is to create another wall or ceiling next to the original but separated from it. The main types of plasterboard available in the UK include the following: Standard plasterboard (1200mmx2400mm) – White Sound Resistant Plasterboard - Blue. Also known as acoustic plasterboard Fire-resistant Plasterboard - Pink Moisture Resistant Plasterboard - Green Insulated Plasterboard - White Plasterboard- product details Inner layer of gypsum sandwiched between two outer layers of lining paper. Additives can be added to the gypsum layer plus the weight and strength of the lining paper varied to give different properties. Fire-resistant rated by testing- Up to 4-hours is possible. Plasterboard reduces sound transmission, particularly airborne sounds such as speech and music. High performance sound insulation board has a denser core. Plasterboard shouldn’t be used in constantly damp conditions. but moisture resistant boards are available. Tapered edge or square edge for jointing or skimming. Standard plasterboard size is 2400 x 1200 to suit 400/600mm spacings. Other sizes are available.  Wallboard Low cost internal lining board providing a degree some sound, fire and impact resistance. Available thicknesses include: 9.5mm 12.5mm- £5.29/sheet 15 mm 10 kg/m2 boards- rated by weight rather than thickness. Provide sufficient acoustic performance for walls and floors. Plank Heavy 19 mm thick plasterboard. 2400 x 600mm. Provides significant mass in a single layer. Used as an inner layer on timber- and steel-framed separating walls and within the ceilings of timber separating floors and as a floating floor. Sound insulation board Higher levels of sound insulation than normal wallboard. Acoustic boards are heavier than standard wallboards and have modified gypsum cores to enhance the acoustic performance. These modifications achieve performances up to 5 dB Rw higher than the standard wallboard. Impact resistant board Twice the impact strength of standard wallboard with a dense gypsum core reinforced with glass fibres and a high strength paper liner. Increased levels of fire resistance and acoustic performance compared with standard wallboard. Provides a robust internal lining for common areas e.g. apartments, student accommodation and hotels. E.g. British Gypsum Multiboard Moisture resistant boards For areas exposed to high levels of moisture. Gypsum core protected by moisture-resistant additives. Coated on both sides with water-repellent liners. BS EN 520: 2004 requires that the boards when submerged in water for 2 hours must not absorb more than 5% water by weight. Fire resistant boards Non-combustible core contains glass fibres and other additives to give superior fire-resistant qualities. Fire-resistance depends upon the system used- not solely the plasterboard. Available in 12.5 mm and 15 mm thickness. £7.95/12.5mm sheet. Vapour check plasterboard Vapour check performance is achieved by laminating a vapour control membrane to the back face of the board. Internal lining of timber- or steel-framed external walls. Ceiling lining to roof space.  Thermal laminates Enhanced thermal performance for walls and ceilings. Especially useful in refurbishment. Variable thickness of insulation for desired performance. Thermaline BASIC 9.5mm board + 30mm insulation = £18.49/sheet. Plasterboard and sustainability Approximately 2 million tonnes of plasterboard are manufactured and sold in the UK each year. 1-1.3 million tonnes of plasterboard waste is generated each year. Plasterboard and sustainability Gypsum containing materials are not permitted in landfill because it is a high sulphate material. Options are: 1. Disposal at a mono-cell landfill site. 2. Recycle or reuse. Reducing plasterboard waste Waste targets Incentivise operatives (snagging and waste) Design to minimise waste Rationalise board types Standard divisions of board widths for claddings Avoid design changes Suitable storage and handling Minimise site damage Only fit in a water tight building Accurate service positioning Transmission of sound Sound resistance Sound can be defined as vibrations of air that are registered by the human ear. All sounds are produced by a vibrating object which causes tiny particles of air around it to move in unison. These displaced air particles collide with adjacent air particles, setting them in motion and in unison with the vibrating object. This continuous chain reaction creates a sound-wave which travels through the air until at some distance the air particle movement is so small that it is inaudible to the human ear. Sounds are defined as either impact or airborne sound, the definition being determined by the source producing the sound. Impact sounds are created when the fabric of structure is vibrated by direct contact whereas airborne sound only sets the structural fabric vibrating in unison when the emitted sound-wave reaches the enclosing structural fabric. The vibrations set up by the structural fabric can therefore transmit the sound to adjacent rooms, which can cause annoyance, disturbance of sleep and of the ability to hold a normal conversation. The objective of sound insulation is to reduce transmitted sound to an acceptable level, the intensity of which is measured in units of decibels (dB). Sound transmission The Building Regulations require certain minimum standards of sound insulation for the building envelope and those internal walls and floors which protect the rooms in dwellings where people work and live The new Regulations also require sample (1 in 10) pre-completion testing to make sure the sound resistance is adequate. Pre completion testing can be avoided by using Robust Details. Sound resistance The Building Regulations, Approved Document E: Resistance to the passage of sound, establishes sound insulation standards as follows: E1: Between dwellings and between dwellings and other buildings. E2: Within a dwelling, i.e. between rooms, particularly WCs and habitable rooms, and bedrooms and other rooms. E3: Control of reverberation noise in common parts (stairwells and corridors) of buildings containing dwellings, i.e. flats. E4: Specific applications to acoustic conditions in schools. Note: E1 includes hotels, hostels, student accommodation, nurses’ homes and homes for the elderly, but not hospitals and prisons. Robust details The robust details® scheme is an alternative solution to pre-completion sound testing for complying with the requirements of A.D. E by providing construction details that provide the necessary level of sound insulation for various applications. Building Regulations Approved Document E The Passage of Sound Doc E Sound requirements Residential requirements Doc E requirements Terms Doc E glossary Robust details Robust details These are guidance constructions as detailed in the new Approved Document ‘E’ which, provided they are built correctly, are deemed to achieve the new Part E performance criteria. Separating walls – masonry Separating walls – timber Separating walls – steel Cavity barriers Cavity barriers should be provided at all of the following locations: at the edges of cavities, including around openings (such as windows, doors and exit/entry points for services) at the junction between an external cavity wall and every compartment floor and compartment wall at the junction between an internal cavity wall and every compartment floor, compartment wall or door assembly forming a fire resisting barrier. It is not appropriate to complete a line of compartment walls by fitting cavity barriers above them. Compartment walls should extend to the underside of the floor or roof above. Cavity barriers in a stud wall or partition, or provided around openings, may be made of: steel, a minimum of 0.5mm thick timber, a minimum of 38mm thick polythene-sleeved mineral wool, or mineral wool slab, under compression when installed in the cavity. In the case of an external wall construction of a building which is not subject to the provisions of Table 9.1, the surfaces which face into cavities should also meet the provisions of Table 12.1 and Section 9 unless Regulation 7(2) applies. Cavity barriers Compartmentation All of the following should be provided as compartment walls and should have, as a minimum, the fire resistance given in Table 7.6.2. A wall common to two or more buildings should be a compartment wall. Parts of a building occupied mainly for different purposes should be separated from one another by compartment walls and/or compartment floors. Compartmentation is not needed if one of the different purposes is ancillary to the other. Effective compartmentation relies on both of the following. Fire resistance should be continuous at the join between elements forming a compartment. Any openings between two compartments should not reduce the fire resistance. Walls surrounding a protected shaft are considered to be compartment walls or compartment floors. Places of special fire hazard should be enclosed by fire resisting construction (minimum REI 30). These walls are not compartment walls. In buildings in a non-residential purpose group the following should be compartment walls: every wall that divides the building to obey the compartment size limits in Table 8.1 and Diagram 8.1a if the building comprises ‘shop and commercial’, ‘industrial’ or ‘storage’, every wall or floor dividing a building into separate occupancies. All compartment walls should achieve both of the following. form a complete barrier to fire between the compartments they separate have the appropriate fire resistance, as given in Appendix B, Tables B3 and B4. Compartmentation Timber beams, joists, purlins and rafters may be built into or carried through a masonry or concrete compartment wall if the openings for them are both as small as practicable and fire-stopped. If trussed rafters bridge the wall, failure of the truss due to a fire in one compartment should not cause failure of the truss in another compartment. Adjoining buildings should only be separated by walls, not floors. Compartment walls common to two or more buildings should run the full height of the building in a continuous vertical plane and be continued through any roof space to the underside of the roof. Compartment walls forming a separated part of a building should run the full height of the building in a continuous vertical plane. Separated parts can be assessed independently to determine the appropriate standard of fire resistance in each. The two separated parts can have different standards of fire resistance Compartment walls not described above should run the full height of the storey in which they are situated. Compartment walls in a top storey beneath a roof should be continued through the roof space. At the junction with another compartment wall or an external wall, the fire resistance of the compartmentation should be maintained. Fire-stopping should be provided. At the junction of a compartment floor and an external wall with no fire resistance, the external wall should be restrained at floor level. The restraint should reduce movement of the wall away from the floor if exposed to fire. Compartment walls should be able to accommodate deflection of the floor when exposed to fire. Where compartment walls are located within the middle half of a floor between vertical supports the deflection may be assumed to be 40mm unless a smaller value can be justified by assessment Junction of a compartment wall with roof A compartment wall should both meet the underside of the roof covering or deck. Fire-stopping should maintain the continuity of fire resistance and be continued across any eaves. To reduce the risk of fire spreading over the roof from one compartment to another, a 1500mm wide zone of the roof, either side of the wall, should have a covering classified as BROOF(t4), on a substrate or deck of a material rated class A2-s3, d2 or better. Double-skinned insulated roof sheeting should incorporate a band of material rated class A2-s3, d2 or better, a minimum of 300mm in width, centred over the wall. As an alternative a compartment wall may extend through the roof for a minimum of either: where the height difference between the two roofs is less than 375mm, 375mm above the top surface of the adjoining roof covering Openings in compartmentation Openings in a compartment wall, that is common to two or more buildings or between different occupancies in the same building, should be limited to those for the passage of a pipe or a fire doorset (these should have the same fire resistance as the wall). Openings in other compartment walls should be limited to those fire doorsets, pipes, ventilation ducts, service cables, chimneys, refuse chutes of class A1 construction, atria or protected shafts. The external wall of a protected shaft does not usually require fire resistance. If a wall common to two or more buildings forms part of the enclosure, openings may be made in that wall for a fire door that provides a means of escape or for the passage of a pipe. Pipes passing through a fire-separating element, unless in a protected shaft, should comply with one of the alternatives A, B or C. Alternative A: Proprietary seals (any pipe diameter) Alternative B: Pipes with a restricted diameter Alternative C: Sleeving. Every joint, imperfect fit and opening for services through a fire-separating element should be sealed with fire-stopping to ensure the fire resistance of the element is not impaired. Fire-stopping delays the spread of fire and, generally, the spread of smoke as well. Escape routes If a corridor is used for a means of escape but is not a protected corridor, any partitions should continue to the soffit of the structural floor above, or to a suspended ceiling. The cavity on the lower side of a fire resisting ceiling that extends throughout the building, compartment or separated part should be protected Escape route design Number of escape routes and exits 2.3 The number of escape routes and exits that should be provided depends on both of the following. a. The number of occupants in the room, tier or storey. b. The limits on travel distance to the nearest exit given in Table 2.1 (which apply only to the nearest exit; other exits may be further away). 2.4 In multi-storey buildings, if more than one stair is needed for vertical escape, every part of each storey should have access to more than one stair. An area may be in a dead end provided the alternative stair is accessible. 2.5 In mixed use buildings, separate means of escape should be provided from any storeys or parts of storeys used for the ‘residential’ or ‘assembly and recreation’ purpose groups (purpose groups 1, 2 and 5). Single escape routes and exits 2.6 A single escape route is acceptable for either of the following. a. Parts of a floor from which a storey exit can be reached within the limit for travel distance in one direction shown in Table 2.1 (see also paragraph 2.8), provided the following apply. i. For places of assembly and bars, no one room in this situation has more than 60 people. ii. For ‘residential (institutional)’ buildings (purpose group 2(a)), no one room in this situation has more than 30 people. Occupant number calculations are described in Appendix D. b. A storey with no more than 60 people, where the limits on travel distance in one direction only are satisfied (see Table 2.1). 2.7 In many cases, the beginning of a route will not have an alternative escape route (for example, a single exit from a room into a corridor where escape is possible in two directions). This is acceptable if both of the following apply. a. The travel distance to the nearest storey exit is within the limits for routes where escape is possible in more than one direction (Table 2.1). b. The travel distance for the ‘one direction only’ section of the route does not exceed the limit for travel distance where there is no alternative escape route (Table 2.1). Diagram 2.1 shows how to measure travel distances from a dead end in an open storey layout. Limitations on travel distances Fire resistance B19 Common to all of the provisions of Part B of the Building Regulations is the property of fire resistance. Fire resistance is a measure of one or more of the following. a. Resistance to collapse (loadbearing capacity), which applies to loadbearing elements only, denoted R in the European classification of the resistance to fire performance. b. Resistance to fire penetration (integrity), denoted E in the European classification of the resistance to fire performance. c. Resistance to the transfer of excessive heat (insulation), denoted I in the European classification of the resistance to fire performance. B20 The standards of fire resistance necessary for a particular building are based on assumptions about the severity of fires and the consequences should an element fail. Fire severity is estimated in very broad terms from the use of the building (its purpose group), on the assumption that the building contents (which constitute the fire load) are similar for buildings with the same use. B21 Because the use of buildings may change, a precise estimate of fire severity based on the fire load due to a particular use may be misleading. Therefore if a fire engineering approach of this kind is adopted, the likelihood that the fire load may change in the future needs to be considered. B22 Performance in terms of the fire resistance to be achieved by elements of structure, doors and other forms of construction is classified in accordance with one of the following. a. BS EN 13501-2. b. BS EN 13501-3. c. BS EN 13501-4. 23 Fire resistance is measured in minutes. This relates to time elapsed in a standard test and should not be confused with real time. B24 The fire resistance necessary for different circumstances is set out in the following tables. a. Table B3 gives the specific requirements for each element of structure. b. Table B4 sets out the minimum periods of fire resistance for elements of structure. c. Table B5 sets out limitations on the use of uninsulated fire resisting glazed elements. What we have covered today Definition Early partition system Modern load bearing partitions Modern non-load bearing partitions Dry lining Building Regulations. Internal load-bearing wall Internal load-bearing walls are walls which provide separation between the internal spaces of a building in addition to being required to transfer loads from the structure to the foundation. Differentiating between load-bearing AND NON- LOAD BEARING WALLS Identifying Loadbearing Walls Video Non-Load Bearing Walls ❖A non-load bearing wall is a wall which doesn’t help the structure to stand up and holds up only itself. ❖Non-load bearing walls do not support roof loads. ❖Most of the time, non-load-bearing walls are interior walls whose purpose is to divide (partition) the structure into separate rooms. ❖They are built lighter and can be removed without endangering the safety of the building. ❖Curtain walls are an example of non- load-bearing walls. Any questions