Insulation Requirements and Specifications under the Saudi Building Code (SBC)

The short answer: what satisfies the code for roofs and tanks?

The question owners ask most is: «How many centimetres of insulation does the code require?». The accurate answer is that the Saudi Energy Conservation Code for Residential Buildings (SBC 602) does not prescribe a thickness for any particular material. It sets a maximum thermal transmittance (U-value) for the complete element: the concrete slab, the screed to falls, the thermal insulation, the waterproofing, the tiles, and the internal and external surface air resistances. A given thickness of a high-performance material may therefore be enough, while a less efficient material needs more thickness to reach the same value.

According to the SBC 602 (2018 edition) text we verified, the maximum U-value for the roof of a conditioned residential building is 0.202 W/m²·K in climate zone 1, 0.238 in zone 2 and 0.273 in zone 3. For a typical 20 cm concrete roof slab with a screed to falls, these limits translate in practice to roughly 8–11 cm of closed-cell spray polyurethane foam, or roughly 9–13 cm of extruded polystyrene (XPS) boards, depending on the zone and the declared thermal conductivity of the product. The detailed calculations are in the worked-examples section below.

Tanks have no U-value limit in SBC 602, because the code addresses the envelope of the conditioned building. For a tank, the criteria are watertight waterproofing and a lining material suitable for contact with drinking water. The Residential Building Construction Requirements issued by the Ministry of Municipal and Rural Affairs and Housing (1446 AH / 2024) require watertight waterproofing inside and outside the ground water tank to prevent seepage. Practical details are on the tank insulation page.

The reference framework: which code governs what?

The Saudi Building Code is a family of numbered parts, each with a defined scope. Mixing up the numbers is common in quotations and specifications; one example is attributing foundation and soil requirements to SBC 305, which is actually the masonry code (brick and block construction). The 2024 Residential Building Construction Requirements list the codes that must be followed, including: the General Building Code SBC 201, the structural codes SBC 301–309, the Electrical Code SBC 401, the Mechanical Code SBC 501, the Energy Conservation Code for Residential Buildings SBC 602, the Plumbing Code SBC 701, the Private Sewage Code SBC 702, the Fire Protection Code SBC 801, and the Residential Building Code SBC 1101–1102.

What exactly does SBC 602 regulate in the building envelope?

• Roofs and above-grade exterior walls: a maximum U-value for each climate zone (the figures are in the zone table below).
• Windows and vertical glazing: the code text gives a U-value of 2.668 W/m²·K for vertical glazing in all three zones, based on a glazed area of up to 25% of the wall area, together with a limit on the solar heat gain coefficient.
• Air leakage: no more than 1.5 L/s per m² at a 75 Pa pressure difference for windows and sliding doors, and 2.5 L/s/m² for swinging doors.
• Continuity: the code treats insulation as a continuous envelope layer, so thermal bridges (columns, beams, opening reveals) affect the real result even when the board looks sufficient on paper.

The role of the Saudi Standards, Metrology and Quality Organization (SASO)

The code sets the performance of the building element, while SASO regulates the conformity of products placed on the market through its technical regulations and the «SABER» conformity certificate platform. In practice, the owner or supervising office asks the supplier for proof that the insulation material conforms to the relevant Saudi regulations and standards, together with a technical data sheet declaring thermal conductivity by a recognised test method. Some quotations circulate specific standard numbers attributed to SASO; we could not verify them in SASO's published sources, so we do not repeat them here. Ask the supplier for the actual certificate number and check it on SABER.

SBC 602 climate zones and how to identify your project's zone

SBC 602 divides the Kingdom into three climate zones according to the severity of the cooling load. Studies applying the code describe them as: zone 1 extremely hot, zone 2 very hot and zone 3 hot, based on cooling degree days (CDD). What surprises many people is that the numbering runs the opposite way to what they expect: zone 1 is the hottest and has the strictest U-value limits, while zone 3 covers the highlands and the northern fringes with the lowest cooling load.

Nor is the division coastal versus inland. Studies applying the code placed Riyadh, Jeddah and Dammam all in zone 1, while Tabuk, Hail and Arar were placed in zone 2 and Abha in zone 3. This contradicts a common assumption that puts Jeddah and Dammam in zone 2. The code refers the determination of a site's zone to its climatic information chapter, so the decisive reference for any city not named in the sources is that table or the project's licensed designer.

How U is calculated, and what is wrong with common R-value tables

Each layer of the roof resists heat flow by an amount equal to its thickness divided by its thermal conductivity. The layer resistances are added to the internal and external surface resistances, and U is one divided by the total.

Some circulating specifications state «30–50 mm foam with R 14 to 20» in US units. That is arithmetically wrong: 50 mm of foam with a conductivity of 0.022 gives R = 0.05 ÷ 0.022 = 2.27 m²·K/W, which is about 12.9 in US units, and 30 mm gives 1.36 m²·K/W, about 7.7 in US units. The table below corrects the figures and shows their effect on a typical concrete roof.

Material specification matrix: what the data sheets actually say

The six materials below are the most common in roof, tank and foundation work. The figures are typical, taken from data sheets for specific products or from reference guides, and they vary from product to product; what counts on any project is the data sheet of the product actually supplied. Note that only two of these are thermal insulants (spray foam and XPS); the rest are waterproofing or concrete protection and contribute almost nothing to the U-value.

Three observations settle many arguments when reviewing quotations. First, the declared k of polyurethane foam changes over time because the gas trapped in the cells gradually exchanges with air, so engineers prefer to calculate with a conservative value (such as 0.026) rather than the best figure in the data sheet. Second, polyurea, membranes, crystalline systems and epoxy are waterproofing or protection materials; adding them to a roof does not change U meaningfully, so they should not be presented in a quotation as «code-compliant thermal insulation». Third, the way conductivity is declared matters: compare products on values declared by a recognised test method, not on marketing phrases. For more on reading these numbers, see the technical data sheet guide.

Worked examples: required thickness for a concrete roof in each zone

Take a typical residential concrete roof: a 200 mm reinforced slab, a 50 mm screed to falls and a waterproofing layer (its thermal resistance ignored). We calculate the insulation resistance needed to meet the SBC 602 limit in each zone and convert it into thickness for two materials: spray foam (k = 0.023, plus a conservative 0.026) and XPS boards (k = 0.027).

1. 1

   Roof resistances before insulation

   Rsi 0.10 + Rse 0.04 + slab 0.20 ÷ 2.3 = 0.087 + screed 0.05 ÷ 1.15 = 0.043, for a total of 0.27 m²·K/W. An uninsulated roof therefore has a U-value of about 3.7 W/m²·K.

2. 2

   Required total resistance

   Total R = 1 ÷ permitted U. Zone 1: 1 ÷ 0.202 = 4.95. Zone 2: 1 ÷ 0.238 = 4.20. Zone 3: 1 ÷ 0.273 = 3.66 m²·K/W.

3. 3

   Resistance required from the insulation

   Subtract 0.27: zone 1 needs 4.68, zone 2 needs 3.93 and zone 3 needs 3.39 m²·K/W from the thermal insulation layer.

4. 4

   Convert resistance to thickness

   Thickness = required R × k. Then round up to the nearest available board thickness, or to a spray thickness that can be verified by measurement.

5. 5

   Check the details

   Add the design corrections: thermal bridges at parapets and columns and, for inverted roofs, a correction for rainwater flowing beneath the boards according to the calculation method the designer uses.

The practical outcome: in zone 1 (Riyadh, Jeddah and Dammam) the roof limit is usually met only with a real thermal insulation layer thicker than 10 cm, or with a build-up combining two materials. This is why the inverted roof is common on residential roofs: continuous waterproofing over the screed, then XPS boards at the calculated thickness, then a ballast or tile layer to protect them. Where spraying is preferred, the foam thickness is calculated with a conservative k and proven by measurement. Field details are on roof insulation in Riyadh and the thermal insulation service.

Tank insulation: what is actually required?

A ground tank faces water pressure from inside and sometimes groundwater or saline soil from outside. It therefore needs three things: watertightness on both faces, as the residential building requirements state; an internal material suitable for drinking water with a recognised certificate; and concrete durability appropriate to the exposure class under SBC 304 in aggressive environments. Thermal insulation of a tank is optional, to moderate water temperature in exposed roof tanks, and is not an SBC 602 requirement.

• Internal lining: epoxy or polyurea designed for drinking water with a certificate such as NSF/ANSI/CAN 61 or BS 6920, applied at the data-sheet thickness (for example, the Jotun data sheet gives 150 microns per coat and a specification range of 150–400 microns).
• Cure before filling: the Jotun Tankguard DW data sheet gives 4 to 14 days before permanent water exposure depending on surface temperature (from 40 down to 10 °C), followed by washing and flushing before use.
• External face and foundations: bituminous or crystalline waterproofing depending on the groundwater level and soil conditions.

Execution conditions: substrate, weather and details

Substrate preparation and moisture

The code sets no figure for concrete moisture before insulation; the reference is the data sheet of the chosen system and the measurement method it specifies. Local specifications often quote «below 4%», and this is indeed a limit given by a well-known manufacturer: the Sikalastic M 689 polyurea data sheet requires substrate moisture of no more than 4% by weight, measured with a Tramex meter, the CM method or oven drying. Other systems use different methods, such as the plastic sheet test ASTM D4263 for capillary moisture, or in-slab relative humidity measurement per ASTM F2170. What matters is that the reading and the method are recorded in the acceptance record.

Corners and upstands

Forming a fillet or cant at the junction of roof and parapet stops the membrane from folding at a sharp angle and reduces cracking. The size commonly used locally is 10×10 cm, but we found no code clause mandating a specific size; the governing size is the one in the system details or the project specification. Published figures include the Canadian Roofing Contractors Association manual, which requires the base flashing membrane to run at least 200 mm up the wall, and the Sika torch-on application guide, which requires laps of at least 6 cm at the sides and 10 cm at roll ends.

Weather and wind

The code contains no temperature or wind limits for application; those limits are set by each product's data sheet. Documented examples: the Sikalastic M 689 data sheet specifies a substrate temperature between 5 and 50 °C and relative humidity no higher than 85%. The BASF SKYTITE foam data sheet offers three reactivity grades for different temperature ranges, including a summer grade for ambient temperatures of roughly 29–49 °C. The membrane application guide advises working in the coolest part of the day in hot climates.

For wind during spraying, we found no numeric limit in a code or general standard that we could quote with confidence. Wind carries foam and polyurea overspray onto nearby cars and buildings, cools the surface and weakens adhesion and layer uniformity. Sound practice: follow the manufacturer's limit where the data sheet gives one, use windscreens, and stop spraying as soon as overspray drift is observed.

Inspection and acceptance: tests that prove workmanship

Flood test

The standard guide ASTM D5957 describes flood testing of horizontal waterproofing on surfaces with a slope of no more than 2%. According to Intertek's summary of the standard, the area is flooded to a depth of at least 25 mm and no more than 100 mm at the lowest point, for a minimum of 24 and a maximum of 72 hours, with the water level monitored in at least two locations. A waterproofing manufacturer's technical bulletin calls for at least 5 cm of water for 24–48 hours. A «5–10 cm» specification is therefore consistent with the standard, whereas «10–15 cm» exceeds the guide's upper limit and adds load the roof may not be designed for.

1. Temporarily plug the drains and divide large roofs into bays.
2. Fill to the specified depth and fix a graduated level marker.
3. Monitor the water level and the soffit below throughout the test, recording observations with timed photographs.
4. If a leak appears: drain, repair per the manufacturer's recommendation, then retest under the same conditions.

Continuity (spark) testing

For non-conductive linings on concrete (polyurea, tank epoxies), ASTM D4787 (external source via the Consumer Safety Center) sets out continuity verification with high-voltage spark testers to detect pinholes, voids and cracks. The test voltage is set according to the coating thickness and the manufacturer's recommendation, not a fixed number. This test is essential in tanks in particular, because a single pinhole in the lining is enough to let water reach the concrete.

Thickness and adhesion verification

• Spray foam: its thickness is the basis of the U calculation, so it is measured with a probe or small cut samples at distributed locations, recorded, and the sample points repaired immediately.
• Coatings and linings: non-destructive ultrasonic measurement per ASTM D6132 (external source via the Consumer Safety Center) for layers up to about 7.6 mm, noting that it is not suitable for coatings that deform readily under load; or destructive measurement on a cut sample where needed.
• Adhesion: pull-off testing on concrete per ASTM D7234, compared with the value declared in the data sheet (for example, 3 N/mm² or concrete failure in the Sikalastic M 689 data sheet).
• XPS boards: confirm that the supplied board thickness and conductivity match the calculation, and check the laps and the presence of the ballast layer.

Documenting compliance: Balady, electricity and the engineering office

For new buildings, compliance follows the permit path: a design that includes envelope calculations under SBC 602, then construction under the supervision of an engineering office. The 2024 Residential Building Construction Requirements state that construction must be supervised by engineering offices accredited by the Ministry, and that roofs must be insulated against moisture and heat and exterior walls treated for thermal insulation. At the end of the project, the building completion certificate is requested through the «Balady» platform; because service requirements are updated, review the current requirements on the platform with your engineering office before applying.

The link between thermal insulation and electricity connection for new buildings has been discussed in the market for years. We could not verify the current form of this requirement from an official published source at the time of writing, so we state no current requirement on behalf of the electricity company. The right step is for the owner to ask the engineering office or the official service channels about the requirements in force before applying.

1. 1

   Before work starts

   Obtain the roof and wall U calculation and the required thickness from the engineering office, and make sure the material in the quotation is the same one used in the calculation.

2. 2

   On delivery

   Request the data sheet, conformity certificate and batch number, and photograph the labels on drums or boards on site.

3. 3

   During the work

   Dated photographs of each stage before it is covered: substrate preparation, primer, waterproofing, thermal insulation with a ruler showing thickness, and the protection layer.

4. 4

   At handover

   Test records (flood, thickness, spark for linings) signed by the supervisor, then the complete file handed over with the warranty document.

Common mistakes in «code-compliant» specifications

• Specifying a fixed thickness instead of a U-value: «5 cm foam, code compliant» means nothing without calculating the build-up and the zone.
• US R-values without distinction: a figure such as R-13 may mean only 2.3 m²·K/W, so ask for the SI value.
• Counting waterproofing towards U: polyurea and membranes do not change U meaningfully.
• Attributing foundations to SBC 305: that is the masonry code; soils and foundations are SBC 303, and concrete durability is SBC 304.
• Unverifiable standard numbers: any standard or certificate number in a quotation must be traceable to its source.
• Flood tests deeper than needed: a depth above 100 mm falls outside the standard guide and loads the roof without adding detection value.

Warranty

Azl provides a written warranty whose duration depends on the insulation type and the roof condition, linked to application per the data sheet and to the documented acceptance file above. Details and exclusions are in the warranty policy. If you have a drawing or calculation from your engineering office and want the proposed system reviewed against it, you can request an inspection.

▶Explaining the thermal transmittance (U-value) calculator and the energy-efficiency guidance manual