10. Flat Roofs p01

Session 10Flat Roofs

10.1. Introduction10.1.1. Elements10.1.2. Standard representations

10.2. Traditional vs protected10.3. Details

10.3.1. International standards10.3.2. Spanish standards

10.4. Case studies10.5. Bibliography

Based on the original presentations by Prof. Juan Alamillo. Adapted by

Prof. Julián García julian.garciam@upm.esTranslated by Luis M. Martín

Flat roof building process at Fuenlabrada Hospital.

Arch. Andrés Perea

10. Flat Roofs p02

10.1. Introduction.Spanish CTE DB HS1 states that flat roofs are those that meet the following slope standards:

But there are many other possible classifications. The international standards are:· Traditional roofs. Waterproof membrane was usually tarpaper, a 'paper' or fiber material soaked or impregnated in tar.· Protected membrane roof. A roof where thermal insulation or another material is placed above the waterproofing membrane.· Composite steel deck. A flat roof deck often used for commercial structures.

10. Flat Roofs p03

10.1.1. Elements.Flat roofs can, according to CTE DB HS-1, include the following elements.· Sloping. Mandatory whenever the support base does not have the required slope.· Vapor barrier. Immediately under the insulation, to avoid humidity by condensation.· Separating layers. Under thermal insulation, under waterproofing membranes, etc. Used to avoid contact of chemically incompatible materials.· Thermal insulation. Appropriate materials.· Protective layers. Over thermal insulation, over waterproofing membranes, etc. Used to avoid cracks or depressions.· Waterproofing layers. To avoid water entrance.· Finishing layer. Various systems.· Drainage system. The drainage system may consist on sinks (vertical) weirs (horizontal) and gutters (linear in edge), or in a combination of them all.

10. Flat Roofs p04

Slope mortars.Construction of the slope of a flat roof with mortar. Lightweight concretes or mortars are often used in Spain.Mind the details about junctions with walls and parapets: a joint to avoid expansion cracks is always mandatory.

10. Flat Roofs p05

Vapor barriers, separating and protecting layers.Vapor barriers, separating and protecting layers can have different forms, and be composed of different materials. For vapor barriers, primers are used, most based on bitumen, improved coal tar or asphalt products. Soft protections or separations are often achieved with polyethylene films, that allow contact of chemically incompatible materials.

10. Flat Roofs p06

Thermal insulation.Its density and thickness is established by the DB-HE-1 CTE. In Madrid climate zone, for a standard 60-90kg/m3 density, the usual thickness is between 8 and 10 cm. The most common material is extruded polystyrene (XPS), due to its low moisture absorption and high durability.

10. Flat Roofs p07

Waterproof membranes.Waterproof membranes are often composed by one of the following materials:· Modified bitumen. Improved coal tar or asphalt products.· EPDM. Ethylene Propylene Diene Monomer, a synthetic rubber.· PVC. Polyvinyl Chloride, also known as vinyl roofing.· FTPO. Flexible Thermo Polyolefin, a polymer that doesn’t cure, and can be heated again.

10. Flat Roofs p08

Finishing layer.Various systems, from loose gravel to standard ceramic tile flooring. Most drained systems use plots to create a cavity between the finishing and the runoff surfaces. In these cases, the roof finishing can be really flat, as the joints between the tiles act as a huge rack that hides water as is flows to the drainage system.

10. Flat Roofs p09

Drainage system.The drainage system usually consists on vertical sinks, most made in EPDM or PVC. Weirs, usually covered with metal racks, are used in pedestrian areas. Gutters in edge are appropriate for pitched roofs.

10. Flat Roofs p010

10.1.2. International graphic standards – Zentralverband des Dachdeckerhandwerks

Waterproofing membrane – Bitumen

Waterproofing membrane – PVCs and EPDMs

Waterproofing membrane – Reinforced membranes

Thermal insulation

Vapour barriers

Separative layers

Mortar layers

Slopes

Protective layers

Drainage layers

10. Flat Roofs p011

Tile finishing. Elastic joints every 3-4m.Cement mortar.Waterproofing layer

Slope

Thermal insulationVapour barrier

Structure or substructure

10.2. Traditional flat roof vs. protected membrane roof.

10. Flat Roofs p012

Protected membrane roof.

Tile finishing. Elastic joints every 3-4m.Cement mortar.Separating layerThermal insulationWaterproofing layer

Slope

Structure or substructure

10. Flat Roofs p013

10.3. Details10.3.1. International standards

10. Flat Roofs p014

10. Flat Roofs p015

10.3.2. Spanish standards

10. Flat Roofs p016

10. Flat Roofs p017

10.3.3. Special junctions. Wall – flat roof.

10. Flat Roofs p018

Special junctions. Drains and overflows.

10. Flat Roofs p019

10.4. Case studiesProtected membrane roof.DANOSA Catalog.

10. Flat Roofs p020

Details. Protected membrane roof.DANOSA Catalog.

10. Flat Roofs p021

Case studiesProtected membrane roof. Plot system.DANOSA Catalog.

10. Flat Roofs p022

Details. Protected membrane roof. Plot system.DANOSA Catalog.

10. Flat Roofs p023

Case studiesProtected membrane roof. Drained system.DANOSA Catalog.

10. Flat Roofs p024

Details. Protected membrane roof. Drained system.DANOSA Catalog.

10. Flat Roofs p025

Case studiesVehicle flat roof.DANOSA Catalog.

10. Flat Roofs p026

Details. Vehicle flat roof.DANOSA Catalog.

10. Flat Roofs p027

Case studiesProtected membrane roof. Loose gravel.DANOSA Catalog.

10. Flat Roofs p028

Protected membrane roof. Loose gravel.DANOSA Catalog.

10. Flat Roofs p029

Case studiesProtected membrane roof. Self-finished roofing felt.DANOSA Catalog.

10. Flat Roofs p030

Details. Protected membrane roof. Self-finished roofing felt.DANOSA Catalog.

10. Flat Roofs p031

Case studiesLightweight deck. Self-finished roofing felt.DANOSA Catalog.

10. Flat Roofs p032

Lightweight deck. Self-finished roofing felt.DANOSA Catalog.

10. Flat Roofs p033

Case studiesIntensive green roof with drainage layer.DANOSA Catalog.

10. Flat Roofs p034

Details. Intensive green roof with drainage layer.DANOSA Catalog.

10. Flat Roofs p035

10.5. Bibliography

Deplazes, A (Ed.) (2009) Constructing Architecture. Materials, processes, structures. Birkhäuser, BaselKnaack, U.; Klein, T. (2009) The Future Envelope 1: A multidisciplinary approach. 2009. Research in Architectural Engineering SeriesKnaack, U.; Klein, T. (2009) The Future Envelope 2: Architecture - Climate – Skin. Research in Architectural Engineering Series Sedlbauer, K. et al. (2010) Roof Construction Manual. Flat Roofs. Birkhäuser, Basel

Spanish regulations:· Código Técnico de la Edificación:· Normas UNE-EN 10077-1, UNE-EN 12210, UNE-EN 12207, UNE-EN 12208, UNE-EN 12400, UNE-EN 12567-1, UNE-EN 14351-1 y UNE-EN -ISO 140-3