The code outlines comprehensive guidelines for constructing flat roof finishes utilizing mud phuska, a traditional method that combines compacted earth with natural binders for insulation and waterproofing. It provides detailed instructions for soil selection, mud mortar preparation, application techniques, protective coatings, and brick tile installation to enhance roof durability and water resistance in warm, arid climates with moderate rainfall.
Overview
The code outlines comprehensive guidelines for constructing flat roof finishes utilizing mud phuska, a traditional method that combines compacted earth with natural binders for insulation and waterproofing. It provides detailed instructions for soil selection, mud mortar preparation, application techniques, protective coatings, and brick tile installation to enhance roof durability and water resistance in warm, arid climates with moderate rainfall.
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Contents
Structure
This section covers the application scope of flat roof finishes using mud phuska and related materials. It specifies the necessary details prior to commencing work, such as the roof surface area, levels, drainage slope direction, parapet wall specifics, and any waterproofing or supplementary treatments beneath the mud phuska. Emphasis is placed on rounding all numerical values according to the IS 2:1960 standard and ensuring all drawings and preparatory instructions are communicated to the roofing team for effective execution.
Clarifies key terms related to mud phuska roofing to ensure uniform understanding. It also reiterates the importance of rounding test and design values as per IS 2-1960, maintaining the number of significant figures consistent with the specified parameters. The section highlights the pre-work information essential for planning, including roof dimensions, slope, parapet details, and waterproofing measures, and mandates transmitting this data to the personnel responsible for roof finishing.
Details the necessary planning information such as roof area, levels, slope direction for drainage, and waterproofing requirements. It stresses coordination among all parties involved, ensuring drawings and instructions are shared before starting the work. Protection from moisture ingress is covered, requiring waterproofing of the sub-floor and extending up to 150 mm above the sub-floor level on adjacent walls. Design specifications include slope gradients, waterproofing materials, mud phuska thickness, and parapet construction details.
Focuses on preventing moisture penetration through waterproofing and damp-proofing treatments. Waterproofing should be applied up to 150 mm above the sub-floor on walls adjoining the roof slab. Materials for waterproofing must conform to relevant IS standards including those for burnt clay tiles, cement types, sand, and pozzolana. The section also outlines proper curing by keeping the finished surface moist for a minimum of seven days and stresses attention to roof-parapet junctions to avoid leakage.
Lists the materials referenced for mud phuska roof finishes, including burnt clay pozzolana, terracing tiles (machine and hand-made), various types of Portland cement, sand for masonry mortars, and masonry mortar preparation codes. It reiterates the importance of rounding off test results as per IS 2-1960 and emphasizes waterproofing measures against dampness. Typical properties for burnt clay pozzolana tiles are provided, along with a schematic depicting material relationships.
Specifies that the sub-floor must be level and even to facilitate proper application of roof finishes and prevent water pooling. Waterproofing is essential if moisture infiltration is anticipated, extending at least 150 mm above the sub-floor on walls. Mortar for grouting should consist typically of a 1:3 cement to sand mix, with burnt clay pozzolana suggested as an additive when ordinary cement is used. Relevant IS codes for materials and procedures are referenced.
Describes the soil requirements for mud plaster, including limits on coarse materials, plasticity index, and exclusion of harmful salts. The recommended mud plaster mix includes dry soil, water, wheat straw (6% by mass), and cow dung (12% by mass), allowed to rot for at least seven days with manual pugging for uniformity. Application involves two coats totaling at least 25 mm thickness, with drying intervals and crack filling using grout. Surface slope and flatness must be verified and corrected as necessary.
Details the composition of leeping plaster made by mixing fine soil free from coarse particles with an equal volume of cow dung and water to form a thin paste. Optionally, 5% cutback bitumen by dry soil mass can be added for enhanced waterproofing. The coating, applied at a minimum thickness of 3 mm over dried mud plaster, requires drying and inspection for cracks, which are to be filled with binder grout. The finish is smoothed with a trowel or float to ensure effective protection.
Specifies that brick tiles used for paving must conform to IS 2690 (Parts I and II). Tiles are laid flat on a thin bed of mud mortar with joint thickness between 6 and 15 mm, mortar rising about 15 mm vertically in joints. A drying period of 24 hours before grouting is essential to avoid tile displacement. Waterproofing below and adjacent to the paving is necessary if moisture percolation is a concern, with treatments extending 150 mm above sub-floor level.
Addresses the durability of mud phuska finishes in hot, dry climates with moderate rainfall, emphasizing the need to maintain protective layers free from cracks and dislodged joints to prevent water ingress. Regular inspections are advised at key stages of the finishing process, including before and after applying mud phuska, mud plaster, and brick tile layers. Waterproofing measures around side walls and parapets must be maintained, and prompt repair of any defects is vital for prolonging the roof's service life.
Frequently Asked
For mud phuska, the soil should be free from gravel and coarse sand larger than 2 mm, with coarse material content not exceeding 25% by weight, no vegetable matter or fine kankar particles, and devoid of harmful or efflorescent salts. Its plasticity index should range between 10% and 15%, and the soil type should be comparable to that used in brick manufacturing, avoiding areas infested by white ants. For mud mortar and plaster, the soil must be free from roots, gravel, and coarse sand over 2 mm, with a maximum coarse material content of 10% by mass, free from harmful salts, and a plasticity index between 10% and 15%. The soil is powdered and mixed with wheat straw (6% by mass) and cow dung (12% by mass), then allowed to rot for at least seven days with manual pugging to achieve a homogeneous mixture.
Mud mortar preparation involves selecting soil free of roots, gravel, and coarse sand over 2 mm, with a plasticity index between 10% and 15%. The soil is mixed with water immediately without the addition of fibrous or binding materials like wheat straw or cow dung; hence, no rotting period is required. To improve water resistance and durability, 2% cutback bitumen by dry soil mass is incorporated into the mixture, ensuring a homogeneous blend suitable for bedding under brick tiles.
The process begins with preparing the leeping plaster by blending fine soil, free from coarse sand and gravel, with an equal volume of cow dung and sufficient water to create a thin, uniform paste. Optionally, 5% cutback bitumen by dry soil mass can be added for additional waterproofing. After the underlying mud plaster has dried for at least 24 hours, any cracks are filled with grout made from the binder used in the leeping plaster. Mud plaster, typically applied in one or two coats totaling 25 mm thickness, is first laid and allowed to dry before applying a minimum 3 mm thick leeping plaster coat. Subsequent crack repairs and surface finishing with a trowel or float complete the protective treatment.
Brick tile paving becomes essential in climates with rainfall or variable temperatures where mud phuska alone does not provide sufficient waterproofing or durability, especially if the roof is intended for habitation or sleeping purposes. The tiles offer a robust, weather-resistant surface that protects the underlying mud layer and enhances thermal insulation. Proper installation involves laying tiles flat on a thin mud mortar bed with joints ranging from 6 to 15 mm, mortar rising about 15 mm vertically in joints, and allowing 24 hours drying before grouting to ensure a level, compact finish.
To maintain durability and waterproofing, the finished roof surface must be kept moist for at least seven days to ensure proper curing. Inspections should be conducted at critical stages: before mud phuska application, after mud phuska finish, after mud plaster finish, and after brick tile installation. Roof levels and slopes must be adequately designed for effective drainage to prevent water accumulation. Waterproofing treatments should be applied beneath the mud phuska layer and extended up to 150 mm above the sub-floor on adjacent walls. Special attention is necessary at junctions between the roof and parapet walls to prevent leakage. Prompt repair of any cracks or defects is crucial to maintaining the roof’s integrity.
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