Interstitial condensation - Revision history

Designing Buildings at 07:09, 5 February 2025

2025-02-05T07:09:01Z

← Older revision		Revision as of 07:09, 5 February 2025
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	Dew point calculators are available that can predict the likelihood of interstitial condensation in different constructions and for different environmental conditions.		Dew point calculators are available that can predict the likelihood of interstitial condensation in different constructions and for different environmental conditions.

−	Condensation in buildings is regulated by Approved Document C (Site preparation and resistance to contaminates and moisture) and Approved Document F (Ventilation) and further guidance is available in BS 5250 Code of practice for the control of condensation in buildings.	+	Condensation in buildings is regulated by Approved Document C (Site preparation and resistance to contaminates and moisture) and Approved Document F (Ventilation) and further guidance is available in BS 5250 Code of practice for the control of condensation in buildings. Approved document C, 2004 edition incorporating 2010 and 2013 amendments defines interstitial condensation as: ‘Deposition of liquid water from a vapour, occurring within or between the layers of the building envelope.’

−	= Related articles on Designing Buildings ~~Wiki~~ =	+	= Related articles on Designing Buildings =

	* Breather membrane.		* Breather membrane.

Designing Buildings at 08:20, 21 September 2020

2020-09-21T08:20:46Z

← Older revision		Revision as of 08:20, 21 September 2020
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	* Warm roof.		* Warm roof.

−	[[Category:~~Theory~~]] [[Category:~~Standards_/_measurements~~]] [[Category:~~DCN_Standard~~]] [[Category:Design]]	+	[[Category:DCN_Definition]] [[Category:DCN_Guidance]] [[Category:Theory]] [[Category:Standards_/_measurements]] [[Category:Design]]

Designing Buildings at 10:12, 9 March 2020

2020-03-09T10:12:33Z

← Older revision		Revision as of 10:12, 9 March 2020
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	Condensation in buildings is regulated by Approved Document C (Site preparation and resistance to contaminates and moisture) and Approved Document F (Ventilation) and further guidance is available in BS 5250 Code of practice for the control of condensation in buildings.		Condensation in buildings is regulated by Approved Document C (Site preparation and resistance to contaminates and moisture) and Approved Document F (Ventilation) and further guidance is available in BS 5250 Code of practice for the control of condensation in buildings.

−	~~= Find out more =~~	+	= Related articles on Designing Buildings Wiki =
−		+
−	=== Related articles on Designing Buildings Wiki ===	+

	* Breather membrane.		* Breather membrane.
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	* Warm roof.		* Warm roof.

−	[[Category:Theory]] [[Category:Standards_/_measurements]] [[Category:Design]]	+	[[Category:Theory]] [[Category:Standards_/_measurements]] [[Category:DCN_Standard]] [[Category:Design]]

Designing Buildings at 10:42, 10 June 2018

2018-06-10T10:42:01Z

← Older revision		Revision as of 10:42, 10 June 2018
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	* Damp proof course.		* Damp proof course.
	* Damp proof membrane.		* Damp proof membrane.
−	* Defects in brickwork
−	* Defects in stonework.
	* Dew point.		* Dew point.
		+	* Diagnosing the causes of dampness (GR 5 revised).
	* Insulation.		* Insulation.
−	* Inverted roof.
	* Lime run-off.		* Lime run-off.
	* Mould growth.		* Mould growth.
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	* Rising damp.		* Rising damp.
	* Vapour barrier.		* Vapour barrier.
−	* Wall tie failure.
	* Warm roof.		* Warm roof.

	[[Category:Theory]] [[Category:Standards_/_measurements]] [[Category:Design]]		[[Category:Theory]] [[Category:Standards_/_measurements]] [[Category:Design]]

Editor at 15:04, 17 April 2018

2018-04-17T15:04:00Z

← Older revision		Revision as of 15:04, 17 April 2018
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	* Insulation.		* Insulation.
	* Inverted roof.		* Inverted roof.
		+	* Lime run-off.
	* Mould growth.		* Mould growth.
	* Penetrating damp.		* Penetrating damp.

Editor at 14:54, 6 December 2017

2017-12-06T14:54:03Z

← Older revision		Revision as of 14:54, 6 December 2017
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	* Damp.		* Damp.
	* Cavity wall.		* Cavity wall.
−	* Cold bridge	+	* Chemical injected DPC.
		+	* Cold bridge.
	* Condensation.		* Condensation.
	* Damp proof course.		* Damp proof course.

Editor at 13:50, 12 November 2017

2017-11-12T13:50:19Z

← Older revision		Revision as of 13:50, 12 November 2017
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	* Dew point.		* Dew point.
	* Insulation.		* Insulation.
		+	* Inverted roof.
	* Mould growth.		* Mould growth.
	* Penetrating damp.		* Penetrating damp.

Editor at 12:33, 12 November 2017

2017-11-12T12:33:22Z

← Older revision		Revision as of 12:33, 12 November 2017
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−
	Air will generally include moisture in the form of water vapour.		Air will generally include moisture in the form of water vapour.

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	Interstitial condensation commonly occurs when moist air permeates through elements of the building fabric, across which there is a temperature difference, typically, but not always, when warm, moist, internal air moves towards the cooler outer parts of external walls or roofs, driven by a pressure difference. If the temperature drops sufficiently, the dew point may be reached within the fabric and condensation will occur.		Interstitial condensation commonly occurs when moist air permeates through elements of the building fabric, across which there is a temperature difference, typically, but not always, when warm, moist, internal air moves towards the cooler outer parts of external walls or roofs, driven by a pressure difference. If the temperature drops sufficiently, the dew point may be reached within the fabric and condensation will occur.

−	If this happens, for example, in the outer leaf of a brick cavity wall, it may cause no more problems than rain does when it wets external walls, simply evaporating over time. However, if it occurs in the inner components, or in insulation it can cause problems:~~<br/>~~	+	If this happens, for example, in the outer leaf of a brick cavity wall, it may cause no more problems than rain does when it wets external walls, simply evaporating over time. However, if it occurs in the inner components, or in insulation it can cause problems:
−	*Mould growth, which is a cause of respiratory allergies.	+
−	*Mildew.	+	* Mould growth, which is a cause of respiratory allergies.
−	*Staining.	+	* Mildew.
−	*Corrosion and decay of the building fabric.	+	* Staining.
−	*Frost damage.	+	* Corrosion and decay of the building fabric.
−	*Poor performance of insulation and reduced thermal resistance of other elements of the building fabric. This in turn can reduce the temperature of the building fabric, exacerbating the condensation problem.	+	* Frost damage.
−	*Migration of salts.	+	* Poor performance of insulation and reduced thermal resistance of other elements of the building fabric. This in turn can reduce the temperature of the building fabric, exacerbating the condensation problem.
−	*Liberation of chemicals.	+	* Migration of salts.
−	*Damage to equipment.	+	* Liberation of chemicals.
−	*Electrical failure.	+	* Damage to equipment.
		+	* Electrical failure.

	Interstitial condensation tends to occur on the warm side of vapour resistant layers.		Interstitial condensation tends to occur on the warm side of vapour resistant layers.

	To prevent this, buildings need to be designed so that the temperature profile across the construction remains higher than the dew point temperature:		To prevent this, buildings need to be designed so that the temperature profile across the construction remains higher than the dew point temperature:
−	*Vapour control layers (VCL) can be positioned on the warm side of insulation, however, these layers must be carefully sealed and penetrations avoided.	+
−	*Materials with low vapour resistance can be positioned on the cooler side of the construction (although this can be problematic where for example the external cladding is impermeable).	+	* Vapour control layers (VCL) can be positioned on the warm side of insulation, however, these layers must be carefully sealed and penetrations avoided.
−	*Ventilated cavities can be provided near the cooler side of the construction.	+	* Materials with low vapour resistance can be positioned on the cooler side of the construction (although this can be problematic where for example the external cladding is impermeable).
−	*Cold bridges can be eliminated.	+	* Ventilated cavities can be provided near the cooler side of the construction.
−	*The moisture in the building itself can be reduced by replacing flue-less gas or oil heaters, improving ventilation and so on. Ventilation can be humidity activated.	+	* Cold bridges can be eliminated.
−	*The internal temperature of the building can be increased. Heating can be thermostatically controlled.	+	* The moisture in the building itself can be reduced by replacing flue-less gas or oil heaters, improving ventilation and so on. Ventilation can be humidity activated.
		+	* The internal temperature of the building can be increased. Heating can be thermostatically controlled.

	Dew point calculators are available that can predict the likelihood of interstitial condensation in different constructions and for different environmental conditions.		Dew point calculators are available that can predict the likelihood of interstitial condensation in different constructions and for different environmental conditions.
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	=== Related articles on Designing Buildings Wiki ===		=== Related articles on Designing Buildings Wiki ===
−	*Breather membrane.
−	*Humidity.
−	*Damp.
−	*Cavity wall.
−	*Cold bridge
−	*Condensation.
−	*Damp proof course.
−	*Damp proof membrane.
−	*Defects in brickwork
−	*Defects in stonework.
−	*Dew point.
−	*Insulation.
−	*Mould growth.
−	*Penetrating damp.
−	*Rising damp.
−	*Vapour barrier.
−	*Wall tie failure.

−	[[Category:Theory]]	+	* Breather membrane.
−	[[Category:Standards_/_measurements]]	+	* Humidity.
−	[[Category:Design]]	+	* Damp.
		+	* Cavity wall.
		+	* Cold bridge
		+	* Condensation.
		+	* Damp proof course.
		+	* Damp proof membrane.
		+	* Defects in brickwork
		+	* Defects in stonework.
		+	* Dew point.
		+	* Insulation.
		+	* Mould growth.
		+	* Penetrating damp.
		+	* Rising damp.
		+	* Vapour barrier.
		+	* Wall tie failure.
		+	* Warm roof.
		+
		+	[[Category:Theory]] [[Category:Standards_/_measurements]] [[Category:Design]]

Designing Buildings at 10:41, 6 August 2015

2015-08-06T10:41:03Z

← Older revision		Revision as of 10:41, 6 August 2015
Line 51:		Line 51:
	*Dew point.		*Dew point.
	*Insulation.		*Insulation.
		+	*Mould growth.
	*Penetrating damp.		*Penetrating damp.
	*Rising damp.		*Rising damp.

Designing Buildings at 15:31, 16 July 2015

2015-07-16T15:31:34Z

← Older revision		Revision as of 15:31, 16 July 2015
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	=== Related articles on Designing Buildings Wiki ===		=== Related articles on Designing Buildings Wiki ===
		+	*Breather membrane.
	*Humidity.		*Humidity.
	*Damp.		*Damp.