waterproofing versus dampproofing (1)

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Waterproofing And Dampproofing



Waterproofing verses Dampproofing

There is a distinct difference between dampproofing andwaterproofing. Dampproofing is intended to keep out soilmoisture while waterproofing keeps out both moisture andliquid water. The International Residential Code (IRC), inSection R406, specifies the conditions that require eitherdampproofing or waterproofing. Any concrete or masonryfoundation walls "that retain earth and enclose interiorspaces and floors below grade shall be dampproofed fromthe top of the footing to the finished grade." The IRC then provides a list of the permissible materials, which include

bituminous coating and acrylic-modified cement.Waterproofing is only required by the IRC "in areas where ahigh water table or other severe soil-water conditions areknown to exist."



• Dampproofing is a coating, usually asphalt-

based, that is either sprayed on or hand applied

to the outside of the wall. But with proper

surface drainage, correctly installed foundation

drains at the footing, and the absence of

hydrostatic pressure to drive water infiltration,dampproofing can supply adequate and long-

lasting protection for many crawl spaces and

basements.



• Waterproofing a foundation requires the same

care as dampproofing in regard to surfacetreatment and drain pipe, but is much more

exacting in the treatment of the wall itself.



• Damp proofing in construction is a type

of waterproofing applied to

building foundation wallsto prevent moisture

from passing through the walls into interior

spaces. A damp-proof course (often

abbreviated to DPC) is a horizontal barrier in a

wall designed to resist moisture rising throughthe structure by capillary action - a

phenomenon known asrising damp.

http://en.wikipedia.org/wiki/Construction

http://en.wikipedia.org/wiki/Waterproofing

http://en.wikipedia.org/wiki/Foundation_walls

http://en.wikipedia.org/wiki/Capillary_action

http://en.wikipedia.org/wiki/Rising_damp_(structural)




http://en.wikipedia.org/wiki/Capillary_action



http://en.wikipedia.org/wiki/Waterproofing

http://en.wikipedia.org/wiki/Construction



Bituminous Damp proofing

• Bituminous damp proofing materials fall into 2

categories.

-Hot applied and Cold applied



Hot applied

• Hot applied Bituminous dampproofing may be

either coal tar or asphalt.• Both are used majorly in exterior applications.

• Hot applied asphalt DPM is occasionally used

in interiors.• This is applied on the exterior and foundation

walls where dampness is expected from theadjacent soil.

• This applied usually over smooth concrete ormasonry coated with cement or motar.



Criteria Hot applied Cold Applied

1.Exterior

Large Projects xSmall Projects

x

2.Interior x3.Where solvents are

involved x

4.Where breathing isrequired x



• Hot applied DPM is occasionally used in

interior location because of the problems

involved with transporting hot materials andthe danger of operating heating equipments

in interior application sites.



Cold applied damp Proofing

CADP is usually emulsion type.

Its Available either in liquid ,semi-fibrated and

heavy fibrated forms.



Damp proofing treatment in building

Damp proofing treatment in building can be

broadly divided into the following categories

• 1. Treatment of foundation

• 2. Treatment of floors

• 3. Treatment of walls

•

4. Treatment of parapet wall• 5. Treatment to pitched roof



1. Damp proofing treatment to foundation

• Depending upon the depth of the

ground level, the treatment to be given to thefoundation can be subdivided into the

following four categories.

I. Treatment to foundation on ordinary soil

II. Treatment to foundation on damp soil

III. Treatment to basement in ordinary soil.

IV. Treatment to basement in damp soil



• I. Treatment to foundation on ordinary soil

• Building foundation on ordinary soil where the subsoil water table not high is also liable to get damp. Bricks beingporous, brick masonry below ground level can be absorbingmoisture from adjacent ground. This moisture travels up from onecourse to another by capillary action and can make the wall dampfor a considerable height. This can be checked by providing DPC atappropriate place.

• In case of building without basement the base

portion for damp proof course lies at plinth level. In case ofstructure without plinth, DPC should be provided at least 150 mmabove ground level. If the damp proof course is just laid at theground level, earth, dust or leaves might accumulate outside thewall and y the passage of time the level of outside the earth may beraised above theD.P.C.level. In such case, moisture can travel from

outside ground level to brickwork above D.P.C.and hence thepurpose of providing D.P.C. will no be served.



I. Treatment to foundation on ordinary soil



II. Treatment to foundation on Damp soil

• In case of building constructed on damp soil in wet areas, both thewalls as well as the ground floor are liable to become damp due tocapillary rise of moisture from ground. In such case the DPC is laidover the entire area of ground floor including wall thickness.Bitumen felts can be used for damp proofing treatment. Thesequence of lying DPC can be divided in the following steps:

• I. Apply hot bitumen at the rate of 1.5kg/m2 over the prepared surface to serve as primer coat.

• II. Lay bitumen felt in the singe layerover the primer coat.

• III. Apply hot bitumen at the rate of 1.5kg/m2 over the bitumen felt to serve as finishing coat.

• Immediately after laying, the DPC is protected with acourse of brick laid flat on a cushion of fine sand. This preventsdamage to the DPC specification on account of droppage of sharpedge implement or other materials during construction.



II. Treatment to foundation on Damp soil



III. Treatment to basement in ordinary soil

• In sites where subsoil water table is low, or where the hydrostatic pressure is notmuch, the treatment consist in a providing a horizontal DPC over the entire area ofbasement floor and then existing it in the form of vertical DPC on the external face

of the basement walls. The DPC material thus function like waterproof tank on theexternal faces of the basement and keep it dry.

• It is common to use bitumen felt in multiple layers for damp proofing treatment tothe basements. For normal duty treatment or in places where the moisture ingressis not considered excessive, two layers of bitumen felts are used. In case of heavyduty treatment or in places where heavy moisture ingress is encountered, threelayer of bitumen felts are used. The sequence of operations for laying of DPC in a

basement for normal duty treatment can be divided in the following steps.I. Apply hot bitumen at the rate of 1.5kg/m2 over the prepared surface to serve as

primer coat.

II. Lay bitumen felt in a single layer over the primer coat

III. Apply hot bitumen at the rate of 1.5 kg/m2 over the bitumen felt.

IV. Lay another layer of bitumen felt in a single layer over the hot bitumen layer instep III above.

V. Apply hot bitumen at the rate of 1.5kg/m2 over the bitumen felt laid in step IV.



• The horizontal DPC is laid on the smoothened top of thelean concrete bed. The lean concrete should be thick orstrong enough to withstand the construction traffic. As

explained earlier immediately after laying, the DPC isprotected with a course of brick laid flat on a cushion offinesand to prevent to damage to DPC specification onaccount of droppage of sharp edge of implement or othermaterial during construction.

• The vertical DPC is laid continuous with thehorizontal one on the external face of the basement walland it is continued 150mm above the ground level where itis tucked into 65 mm deep groove made in the wall. Thegroove is subsequently filled with cement mortar 1:4. The

vertical D.P.C., unless protected is likely to get punctured byroots of trees or get damaged by salts/acids in the soil.Necessary protection in this regard is given by constructinghalf brick outer skin wall.



IV. Treament to Basement in Damp Soil

• Ground water always produces hydrostatic

pressure and as such poses great problem indesign of basement. In sites where the groundwater table is high, the problem of damp proofingof basement can be tackled by one of the

following methods.I. By providing foundation drains and DPC.

II. By providing RCC floors and wall slab and DPC.

III. Water proofing treatment by using groutconsisting of cement mortar admixed with acrylicbased chemicals along with rough stone slabs.



Damp proofing treatment to floors

• In places where the soil water table is low and rainfall is not much,a 75 to 100 mm thick layer of coarse sand is first spread over theentire area of the flooring on the prepared bed of rammed earth.Alternatively this layer can comprise of stone soling with voids filledwith smaller stones. This layer is known as base course and itsmaterial is well rammed. A75 to 100 mm thick layer of lean cementconcrete (1:3:6 or 1:4:8) mix or lime concrete is thereafter laid overthe base course. This form the base for floor topping which maycomprise of tiles, stone or cement concrete etc.

• In place where the sub soil water is high, or in damp orhumid areas, where there is a possibility of moisture rising up in the

floor, it is necessary to provide membrane DPC of flexible materiallike bitumen felt etc.over the entire area of flooring.



Damp proofing treatment to walls

• The walls can get damp due to penetration of moisturefrom its external face to internal one, due to porosity ofbricks and mortar joints. Various treatments given toexposed surface of the walls to prevent dampness includepointing, plastering and painting etc. It is observed that

plaster made out of cement, lime and sand mixed inproportion of 1:1:6 serves as very effective rendering toprotect the walls against dampness in normal weatherconditions. In areas of heavy rainfall, cement plaster 1: 4mixed with water proofing compounds like Pudlo, Permo,

etc. serve the purpose effectively. In exposed brick work,dampness can be prevented by painting the surface withwater proof cement paint or with colourless liquid waterproofing compound.



Damp proofing treatment to flat roofs

• Flat roof required relatively heavier and costlier water-proofing treatment as compared withpitched or sloped roofs. The specification of material used for the purpose should be such that itshould perform the function of water proofing as well as provides adequate thermal insulation.Stagnation of the water on the roof is considered to be the root cause of leakage and dampness inthe flat roofs. This can be avoided by providing adequate roof slope and rain water pipes. In case ofR.C.C. or R.B.C. slab roofing with proper grading above, a slope of 1:40 to 1:60 is considereddesirable. This may be achieved by varying the thickness of the terracing material or byconstructing the roof slab with a slope, or by providing part slope in the roof slab and part in the

terracing material. In addition to the slope, the size and the spacing of the rain water pipes or theoutlets require due consideration for the proper drainage of the roof. In general practice one 10cmdiameter pipe is considered suitable for every 30 sq.m. of the roof area to be drained.

• In case, where the slope for the drainage of the roof are given in the roof slab itself or insituation where thermal insulation is not important and the problem of slopes in the flat roof istackled suitably, the waterproofing treatment for the roof may consist in laying bitumen felt directlyover the surface of roof slab after painting the roof top with hot bitumen. The bitumen felt may beHessian based or fibre based. Depending upon the type of building, climate and atmosphericconditions of the site, the treatment with the felt may be with four courses, six courses or eight

courses. The four course treatment is recommended for moderate conditions, where as six andeight course treatments are recommended for severe and very severe conditions respectively. The1)Four course treatment and 2)six course treatment are brifly given below.



The following method of grading is adopted to

meet the requirement of water proofing.

• 1. Grading of lime concrete.

• 2. Grading of lime concrete with tiles.

• 3. Grading of mud phuska with tiles.

•

4. Grading of brick coba laid with groutconsisting of cement mortar admixed with

acrylic based chemicals.



Treatment to parapet wall:

• If the flat roof has the parapet and there are crack init or its plaster is very porous or defective, rain watermay find and easy access to the wall below and makethe wall and some portion of the ceiling damp.Rain

water may also leak through cras at the junction of theparapet and roof slab. In case where asphalt layer isprovided over the grading material for thewaterproofing treatment to the roof slab, the asphaltlayer covering the roof is turned up against the parapet

for a height of at least 15 cm. The parapet wall isfurther protected by providing coping of brick,concrete or stone on its top.



Water Proofing in green roof:



Water Proofing in swimming pool:

1.wall panel

2.overflow gutter

3.gravel backfilling

4.natural ground

5.buttress frame

6.base frame7.footing (reinforced concrete)

8.waterproofing material -

reinforced PVC, thickness

1.5mm

9.pool floor with reinforced

mesh10.gravel drainage bed

waterproofing versus dampproofing (1)

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